mysql - 如何使用mysql将查询结果存储在变量中

Question

SET @v1 := SELECT COUNT(*) FROM user_rating;
SELECT @v1

当我使用set变量执行此查询时，会显示此错误。

Error Code : 1064
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use
near 'SELECT count(*) FROM user_rating' at line 1

Execution Time : 00:00:00:000
Transfer Time  : 00:00:00:000
Total Time     : 00:00:00:000

(1 row(s) returned)
Execution Time : 00:00:00:343
Transfer Time  : 00:00:00:000
Total Time     : 00:00:00:343

Answer 1

用括号括住该选择。

SET @v1 := (SELECT COUNT(*) FROM user_rating);
SELECT @v1;

Answer 2

此外，如果您想通过一个查询一次设置多个变量，您可以使用另一种语法来设置变量，如下所示SELECT @varname:=value：

一个实际的例子：

SELECT @total_count:=COUNT(*), @total_price:=SUM(quantity*price) FROM items ...

Answer 3

用这个

 SELECT weight INTO @x FROM p_status where tcount='value' LIMIT 1;

经过测试并且工作正常...

Answer 4

Select count(*) from table_name into @var1; 
Select @var1;