mysql - = 和 := in MySQL 之间的区别

Question

在 MySQL 中，这两个命令有什么区别？

它们工作得很好，结果总是一样的:

set @numRecords = (select count(*) from config);

set @numRecords := (select count(*) from config);

谢谢大卫

Answer 1

引用 MySQL 5.7 引用手册，section 10.4 User-Defined Variables :

For SET, either = or := can be used as the assignment operator.

You can also assign a value to a user variable in statements other than SET. In this case, the assignment operator must be := and not = because the latter is treated as the comparison operator = in non-SET statements