MySQL SET IF 语句
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MySQL SET IF Statement
提问by H. Ferrence
Can someone show me the correct mysql syntax to do the following:
有人可以向我展示正确的 mysql 语法来执行以下操作：
Update a column in a table with 1 of 3 values:
使用 3 个值之一更新表中的列：
If col_A = 4 set col_Z to col_A If col_B = 4 set col_Z to col_B Else set col_Z to NULL (or leave alone because col_Z is initialized to NULL)
如果 col_A = 4 将 col_Z 设置为 col_A 如果 col_B = 4 将 col_Z 设置为 col_B 否则将 col_Z 设置为 NULL（或者不理会因为 col_Z 被初始化为 NULL）
Here's what I have:
这是我所拥有的：
Update my_table
SET col_Z = IF(col_A = 4, col_A, IF(col_B = 4, col_B, NULL))
WHERE id = "001"
IS this correct?
这样对吗？
回答by Johan
Yes, it looks correct.
是的，它看起来是正确的。
The following code will be simpler though.
不过下面的代码会更简单。
UPDATE my_table
SET col_Z = IF(col_A = 4 OR col_B = 4, 4, NULL)
WHERE id = "001"
