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This article mainly introduces what is the use of set in mysql. It is very detailed and has a certain reference value. Interested friends must finish reading it!

SET is a way of assigning values to defined variables in SQL Server and is often used with update statements.

Syntax:

UPDATE table name SET column name = new value WHERE column name = a value

Note:

There are two ways to assign values to defined variables in SQL Server, namely SET and SELECT. The differences between the two ways are as follows:

1. There is a difference when assigning values to multiple variables at the same time:

Set does not support assigning multiple variables.

Select supports the assignment of multiple variables.

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

Set will make an error when returning multiple values to an expression

When select returns multiple values to an expression, it returns the result to the last value assigned to the variable.

3. There is a difference between the values not returned by the expression:

When set returns a value of an expression, the variable is assigned a null value.

When select returns an unreturned value of an expression, the variable maintains its original value.

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