Hướng dẫn replace mysql
Trong bài này mình sẽ hướng dẫn cách sử dụng hàm Bài viết này được đăng tại freetuts.net, không được copy dưới mọi hình thức. 1. Mô tảHàm 2. Cú phápCú pháp của hàm REPLACE( string, from_substring, to_substring ) Trong đó: Bài viết này được đăng tại [free tuts .net]
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3. VersionChức năng
4. Ví dụmysql> SELECT REPLACE('freetuts.net', 'freetuts', 'myfreetuts'); Ket qua: 'myfreetuts.net' mysql> SELECT REPLACE('freetuts.net', 'e', '##########'); Ket qua: 'fr####################tuts.n##########t' mysql> SELECT REPLACE('freetuts.net', 'h', 'y'); Ket qua: 'freetuts.net' mysql> SELECT REPLACE('12345 12345', 4, 5); Ket qua: '12355 12355' 13.2.9 REPLACE Statement
Note Values for all columns are taken from the values specified in the In MySQL 8.0.19 and later, you can specify the column values that To use If a generated column is replaced explicitly, the only permitted value is The The affected-rows count makes it easy to determine whether If you are using the C API, the affected-rows count can be obtained using the
You cannot replace into a table and select from the same table in a subquery. MySQL uses the following algorithm for
It is possible that in the case of a duplicate-key error, a storage engine may perform the Because the results of MySQL 8.0.19 and later supports When modifying an existing table that is not partitioned to accommodate partitioning, or, when modifying the partitioning of an already partitioned table, you may consider altering the table's primary key (see Section 24.6.1, “Partitioning Keys, Primary Keys, and Unique Keys”). You
should be aware that, if you do this, the results of
When we create this table and run the statements shown in the mysql client, the result is as follows:
Now we create a second table almost identical to the first, except that the primary key now covers 2 columns, as shown here (emphasized text):
When we run on
This is due to the fact that, when run on |