Question

我想更新表格，我不知道哪个列会更新。这是一个简单的例子

Update tablename
set 
if col1='A' then col1='IA',col2='XXX'
if col3='A' then col3='IA', col4='XXX'
where
(col1='A' and col2='UNKNOWN') or (col3='A' and col4='UNKNOWN')

此处col1或col3肯定包含'A'

请提供正确的查询

Answer 1

尝试此查询

UPDATE tablename
SET col1=(CASE WHEN col1 LIKE 'A' THEN col1='IA' ELSE col1 END),
col2=(CASE WHEN col1 LIKE 'A' THEN col2='XXX' ELSE col2 END),
col3=(CASE WHEN col3 LIKE 'A' THEN col3='IA' ELSE col3 END),
col3=(CASE WEHN col3 LIKE 'A' THEN col4='XXX' ELSE col4 END)
WHERE
(col1='A' AND col2='UNKNOWN') OR (col3='A' AND col4='UNKNOWN')

Answer 2

过去的帖子，但对于那些偶然发现此问题的Google员工而言。这行不通。例如

THEN col1='IA'

将返回一个布尔值并将col1设置为1，即true 相反，只需返回'IA'和THEN 'IA' ELSE col1 END

为清楚起见：

UPDATE tablename
SET col1=(CASE WHEN col1 LIKE 'A' THEN 'IA' ELSE col1 END),
col2=(CASE WHEN col1 LIKE 'A' THEN 'XXX' ELSE col2 END),
col3=(CASE WHEN col3 LIKE 'A' THEN 'IA' ELSE col3 END),
col3=(CASE WEHN col3 LIKE 'A' THEN 'XXX' ELSE col4 END)
WHERE
(col1='A' AND col2='UNKNOWN') OR (col3='A' AND col4='UNKNOWN')

MySQL：使用If else更新查询

2 个答案: