mysql - 插入错误语法后选择 count(*) 并选择 sum(my_data)#1064

Question

我是sql初学者，甚至是编程，最近发现了触发器，我想计算最大活跃行数，以及活跃权重总和 ps:事件记录定义为“cancelled = 0” 我在声明变量的行(第 2 行)附近遇到错误 #1064

我正在将其运行到 PHPMYADMIN (MySQL) 触发器中。

BEGIN
DECLARE @max_rows int;
DECLARE @max_tare int;
SET @max_rows = SELECT COUNT(*) FROM history WHERE cancled = 0;
SET @max_tare= SELECT SUM(tare) FROM history WHERE cancled = 0;
UPDATE max_tare
SET max_row  = @max_rows,
    max_tare = @max_tare
WHERE id = 1
END

我原以为我会用最大行数和事件权重总和更新第 1 行，但出现错误

MySQL replied: # 1064 - Syntax error near '@max_rows int; DECLARE @max_tare int; SET @max_rows = SELECT COUNT (*) FROM his' at line 2

在 Paul 发表评论后，我将代码更改为:

BEGIN
DECLARE max_r int;
DECLARE max_t int;
SET max_r = SELECT COUNT(*) FROM history WHERE cancled = 0;
SET max_t = SELECT SUM(tare) FROM history WHERE cancled = 0;
UPDATE max_tare
SET max_row  = max_r,
    max_tare = max_t
WHERE id = 1
END

这是新错误:

MySQL replied: # 1064 - Syntax error near SELECT COUNT (*) FROM history WHERE cancled = 0; SET max_t = SELECT SUM (tare) FR 'at line 4

提前。

Answer 1

感谢@paul Spiegel 和@forpas 的帮助 这段代码帮助解决了问题

IF(NEW.mix != '') THEN
UPDATE max_tare
SET max_row  = (SELECT COUNT(*)  FROM history WHERE nom LIKE NEW.mix),
    max_tare = (SELECT SUM(tare) FROM history WHERE cancled = 0)
WHERE id = 1;
ELSE
UPDATE max_tare
SET max_row  = (SELECT COUNT(*)  FROM history WHERE cancled = 0),
    max_tare = (SELECT SUM(tare) FROM history WHERE cancled = 0)
WHERE id = 1;
END IF;
END

这对我来说效果很好，谢谢大家