Question

我在SQL Server中有一个表，其中有一个PK（ID）和另一个（逻辑）主键由其他几列创建（尽管没有UNIQUE约束）。我们先说PERSON，PK = PERSON_ID，然后NAME，SURNAME，AGE

我希望可以说

UPDATE PERSON SET AGE = 43 WHERE NAME = 'XX' AND SURNAME = 'YYY'

并且只有在更新的行＆＃39; = 1，否则（超过1行）根本不执行。问题是我不确定NAME和SURNAME是否唯一地标识了一条记录，我无法先验地说出来。

想法？

Answer 1

尝试以下查询...它会帮助您

UPDATE PERSON 
SET AGE = 43 
WHERE NAME = 'XX' 
  AND SURNAME = 'YYY' 
  AND 1 = (SELECT COUNT(*) FROM PERSON WHERE NAME = 'XX' AND SURNAME = 'YYY)

Answer 2

我在更新之前而不是在where子句中放置条件。

IF (SELECT COUNT(*) FROM PERSON WHERE NAME = 'XX' AND SURNAME = 'YYY') = 1
UPDATE PERSON SET AGE = 43 WHERE NAME = 'XX' AND SURNAME = 'YYY'

Answer 3

我不是编写复杂的WHERE子句或IF语句，而是将整个事物包装在事务中并检查@@ ROWCOUNT：

BEGIN TRAN
UPDATE PERSON SET AGE = 43 WHERE NAME = 'XX' AND SURNAME = 'YYY'
IF @@ROWCOUNT > 1 ROLLBACK TRAN ELSE COMMIT TRAN

Answer 4

类似的东西应该这样做。

UPDATE Person p1
SET p1.AGE = 43
WHERE NAME = 'XX' AND SURNAME = 'YY'
AND NOT EXISTS (
  SELECT NULL FROM Person p2
  WHERE p1.NAME = p2.NAME
  AND p1.SURNAME = p2.SURNAME
  GROUP BY p2.NAME, p2.SURNAME
  HAVING COUNT(*) > 1)

Answer 5

UPDATE Person p1
SET p1.AGE = 43
WHERE NAME = 'XX' AND SURNAME = 'YY'
AND NOT EXISTS (
  SELECT NULL FROM Person p2
  WHERE p1.NAME = p2.NAME
  AND p1.SURNAME = p2.SURNAME
  AND p1.ID <> p2.ID)

如果一行受到影响，如何执行UPDATE？

5 个答案: