Những thứ cơ bản
Để có được số lượng các hàng phù hợp trong SQL, bạn thường sẽ sử dụng
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6. Ví dụ:SELECT COUNT[*] FROM some_table
Để có được giá trị đó trong PHP, bạn cần lấy giá trị từ cột đầu tiên trong hàng đầu tiên của kết quả trả về. Một ví dụ sử dụng PDO và MySQLI được thể hiện dưới đây.
Tuy nhiên, nếu bạn muốn tìm nạp kết quả và sau đó vẫn biết bạn đã tìm nạp bao nhiêu bản ghi bằng PHP, bạn có thể sử dụng
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
7 hoặc tận dụng số lượng được sử dụng trước trong đối tượng kết quả nếu API DB của bạn cung cấp nó, ví dụ: Mysqli's // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
8.Sử dụng MySQLI
Sử dụng MySQLI, bạn có thể tìm nạp hàng đầu tiên bằng cách sử dụng
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
9 và sau đó truy cập cột // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
0, có thể chứa giá trị của // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6. // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
Nếu bạn muốn tìm nạp tất cả các hàng, nhưng vẫn biết số lượng hàng thì bạn có thể sử dụng
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
8 hoặc // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
7.// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
Sử dụng PDO
Sử dụng PDO đơn giản hơn nhiều. Bạn có thể gọi trực tiếp
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
4 trên câu lệnh để nhận một giá trị cột duy nhất.// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
Một lần nữa, nếu bạn cần tìm nạp tất cả các hàng, thì bạn có thể lấy nó bằng hàm
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
7.// your SQL statement
$stmt = $pdo->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// If you want to use the results, but still know how many records were fetched
$rows = $stmt->fetchAll[];
echo count[$rows];
Tuyên bố của PDO không cung cấp thuộc tính được tính toán trước với số lượng hàng được tìm nạp, nhưng nó có một phương thức gọi là
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
6. Phương pháp này có thể cho bạn biết số lượng hàng được trả về trong kết quả, nhưng nó không thể dựa vào và nó thường không được khuyến nghị sử dụng. Tóm tắt: Trong hướng dẫn này, bạn sẽ tìm hiểu cách sử dụng hàm MySQL
7 để trả về các hàng số trong bảng.: in this tutorial, you will learn how to use the MySQL // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 function to return the number rows in a table.Giới thiệu về chức năng MySQL // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
Hàm
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 là một hàm tổng hợp trả về số lượng hàng trong bảng. Hàm // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 cho phép bạn đếm tất cả các hàng hoặc chỉ các hàng phù hợp với một điều kiện được chỉ định.Hàm
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 có ba dạng: // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6, // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
3 và // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
4.Chức năng // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
Hàm
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 trả về số lượng hàng trong một tập kết quả được trả về bởi câu lệnh // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
7. // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 trả về số lượng hàng bao gồm các hàng trùng lặp, không null và // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
9.// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
3
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
3 trả về số lượng hàng không chứa các giá trị // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
9 là kết quả của biểu thức.// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
4
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
4 trả về số lượng các hàng riêng biệt không chứa các giá trị // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
9 là kết quả của biểu thức.Loại trả về của hàm
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 là // your SQL statement
$stmt = $pdo->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// If you want to use the results, but still know how many records were fetched
$rows = $stmt->fetchAll[];
echo count[$rows];
7. ____ 27 & nbsp; Hàm trả về 0 nếu không có hàng phù hợp được tìm thấy.MySQL // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 minh họa chức năng
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
Thiết lập bảng mẫu
Đầu tiên, tạo một bảng có tên
0:
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
Code language: SQL [Structured Query Language] [sql]
Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
Thứ hai, chèn một số hàng vào bảng
0:Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
Code language: SQL [Structured Query Language] [sql]
INSERT INTO count_demos[val] VALUES[1],[1],[2],[2],[NULL],[3],[4],[NULL],[5];
Thứ ba, dữ liệu truy vấn từ bảng
0:Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
Code language: SQL [Structured Query Language] [sql]
SELECT * FROM count_demos;
Ví dụ MySQL // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
Câu lệnh sau sử dụng hàm
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 để trả về tất cả các hàng từ bảng 0:Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
Ví dụ này sử dụng hàmCode language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos;
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 với mệnh đề 7 để chỉ định một điều kiện để chỉ đếm các hàng có giá trị trong cột & nbsp;Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
8 là 2:Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
This example uses the
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 function with a 7 clause to specify a condition to count only rows whose value in the columnCode language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
8 is 2:Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
MysQL
SELECT COUNT[*] FROM count_demos WHERE val = 2;
Code language: SQL [Structured Query Language] [sql]
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
3 Ví dụMySQL // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
3 example
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
Nếu bạn chỉ định cột
8 trong hàmCode language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7, hàm // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 sẽ chỉ đếm các hàng có giá trị không null trong cột & nbsp; ____ 58:// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
0notice rằng hai giá trị // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
9 không được bao gồm trong kết quả.Notice that two
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
9 values are not included in the result.Ví dụ MySQL // your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
4
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
Ví dụ này sử dụng
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
4 để đếm các giá trị không phải null và khác biệt trong cột 8:Code language: SQL [Structured Query Language] [sql]
CREATE TABLE count_demos [ id INT AUTO_INCREMENT PRIMARY KEY, val INT ];
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
1Mysql // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 Các ví dụ thực tế chức năngMySQL // your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 function practical examples
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
Chúng tôi sẽ sử dụng bảng
9 từ cơ sở dữ liệu mẫu cho các ví dụ tiếp theo:Code language: SQL [Structured Query Language] [sql]
INSERT INTO count_demos[val] VALUES[1],[1],[2],[2],[NULL],[3],[4],[NULL],[5];
A] Sử dụng hàm MySQL // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 với ví dụ SELECT * FROM count_demos;
Code language: SQL [Structured Query Language] [sql]
1
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
SELECT * FROM count_demos;
Hàm
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 thường được sử dụng với mệnh đề 1 để trả về số lượng phần tử trong mỗi nhóm.Code language: SQL [Structured Query Language] [sql]
SELECT * FROM count_demos;
Ví dụ: câu lệnh này sử dụng hàm
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 với mệnh đề 1 để trả về số lượng sản phẩm trong mỗi dòng sản phẩm:Code language: SQL [Structured Query Language] [sql]
SELECT * FROM count_demos;
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
2SImilarly, ví dụ này sử dụng hàm // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 để tìm số lượng sản phẩm được cung cấp bởi mỗi nhà cung cấp:Similarly, this example uses the
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 function to find the number of products supplied by each vendor:// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
3b] Sử dụng MySQL // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 với ví dụ mệnh đề 8Code language: SQL [Structured Query Language] [sql]
SELECT * FROM count_demos;
B] Using MySQL // your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 with a SELECT * FROM count_demos;
Code language: SQL [Structured Query Language] [sql]
8 clause example
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
SELECT * FROM count_demos;
Để tìm các nhà cung cấp cung cấp ít nhất 9 sản phẩm, bạn sử dụng chức năng
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
6 trong mệnh đề 8 như trong truy vấn sau:Code language: SQL [Structured Query Language] [sql]
SELECT * FROM count_demos;
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
4C] MySQL 1 Ví dụCode language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos;
C] MySQL SELECT COUNT[*] FROM count_demos;
Code language: SQL [Structured Query Language] [sql]
1 example
SELECT COUNT[*] FROM count_demos;
Bạn có thể sử dụng biểu thức và chức năng lưu lượng điều khiển, ví dụ:
2,Code language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos;
3 và ________ 84 & nbsp; trong hàmCode language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos;
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 để đếm các hàng có giá trị khớp với điều kiện.Xem bảng
6 sau từ cơ sở dữ liệu mẫu:Code language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos;
Truy vấn sau sử dụng
// your SQL statement
$stmt = $mysqli->prepare['SELECT col1, col2 FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// If you want to use the results, but still know how many records were fetched
$rows = $result->fetch_all[MYSQLI_ASSOC];
echo $result->num_rows;
// or
echo count[$rows];
7 với hàm 2 để tìm số lượng đơn đặt hàng bị hủy, giữ và tranh chấp từ bảngCode language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos;
6:Code language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos;
// your connection code
mysqli_report[MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT];
$mysqli = new \mysqli['localhost', 'dbuser', 'yourdbpassword', 'db_name'];
$mysqli->set_charset['utf8mb4'];
// your SQL statement
$stmt = $mysqli->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->bind_param['s', $someVariable];
$stmt->execute[];
$result = $stmt->get_result[];
// now fetch 1st column of the 1st row
$count = $result->fetch_row[][0];
echo $count;
5Thử nó ra
Chức năng ____ 90 & nbsp; trả về 1 nếu trạng thái đơn hàng bị hủy, bị giữ hoặc tranh chấp, nếu không, nó sẽ trả về
// your connection code
$pdo = new \PDO['mysql:host=localhost;dbname=test;charset=utf8mb4', 'root', '', [
\PDO::ATTR_EMULATE_PREPARES => false,
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION
]];
// your SQL statement
$stmt = $pdo->prepare['SELECT COUNT[*] FROM some_table WHERE col1=?'];
$stmt->execute[[
$someVariable
]];
// Fetch the first column of the first row
$count = $stmt->fetchColumn[];
echo $count;
9.Hàm
2 chỉ tính 1, không phải là giá trị null, do đó, truy vấn trả về số lượng đơn đặt hàng dựa trên trạng thái tương ứng.Code language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos WHERE val = 2;
Trong hướng dẫn này, bạn đã học được nhiều kỹ thuật khác nhau để đếm số lượng hàng trong bảng bằng hàm MySQL
2.Code language: SQL [Structured Query Language] [sql]
SELECT COUNT[*] FROM count_demos WHERE val = 2;
Hướng dẫn này có hữu ích không?