What does set mean in mysql?

SET in mysql is a way to assign values ​​to defined variables in SQL Server. It is often used together with the update statement. Its usage syntax is [UPDATE table name SET column name = new value WHERE column name = certain value] .

SET is a way of assigning values ​​to defined variables in SQL Server and is often used together with the update statement.

Syntax:

UPDATE 表名称 SET 列名称 = 新值 WHERE 列名称 = 某值

Note:

There are two ways to assign values ​​to defined variables in SQL Server, namely SET and SELECT. For these two methods The differences are as follows:

1. There are differences when assigning values ​​to multiple variables at the same time:

set does not support assigning values ​​to multiple variables.

select supports assignment to multiple variables.

2. There is a difference when an expression returns multiple values:

set will make an error when it returns multiple values ​​for an expression

select returns multiple values ​​for an expression when the result is returned to the last value assigned to the variable.

3. There is a difference when the expression does not return a value:

set When the expression does not return a value, the variable is assigned a null value.

select When the expression does not return a value, the variable retains its original value.

Related recommendations: "MySQL Tutorial"

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