如何將查詢結果存儲在使用mysql的變量中

Question

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

當我使用set變量執行此查詢時，會顯示此錯誤。

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

用圓括號選擇的環繞聲。

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

Answer 2

此外，如果你想通過一個查詢一次設置多個變量，你可以用其他的語法，用於設置是這樣的變量：SELECT @varname:=value。

一個實際的例子：

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

Answer 3

使用本

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

測試workes精...