发布：2023/4/26 8:54:54作者：管理员 来源：本站 浏览次数：642
第一种：
语法：
UPDATE table1 SET column1 = (SELECT column FROM table2 [WHERE condition])
WHERE table1.column2 = value;
注：若不加where条件则是更新表中的所有数据，
故执行没有where子句的update要慎重再慎重。
第二种：
语法：
UPDATE table1 INNER/LEFT/RIGHT JOIN
table2
/
(
SELECT COLUMNS FROM table3
[INNER/LEFT/RIGHT JOIN ON CONDITION]
[WHERE conditions]
) AS t3
ON CONDITION
SET column1 = value1,column2 = value2,...
[WHERE conditions];
实例1：
UPDATE
$ table1 a
INNER JOIN $ table2 b
ON a.user_id = b.user_id
SET a.balance = a.balance + b.income,
b.status = 1
WHERE b.id = 1
AND b.status = 0;
实例2：
UPDATE
A
INNER JOIN
(SELECT
B.B1 AS B1,
B.B2 AS B2,
C.C1 AS C1
FROM
B
LEFT JOIN C
ON B.B3 = C.C3) AS t
ON A.A3 = t.B1 SET A.A1 = t.B2,
A.A2 = t.C1;
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