postgresql 检查数据库是否为 NULL 布尔值
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Checking database for NULL boolean value
提问by Ben Everard
I have a field in a table that is boolean, a range of records have no value (not true or false). How do I write my SQL statement to find these?
我在一个布尔值的表中有一个字段，一系列记录没有值（不是真或假）。我如何编写我的 SQL 语句来找到这些？
I have tried the following SQL statements without success:
我尝试了以下 SQL 语句但没有成功：
1) SELECT * FROM table WHERE field = NULL
2) SELECT * FROM table WHERE field != TRUE AND field != FALSE
Any help would be greatly appreciated.
任何帮助将不胜感激。
Many Thanks, Ben
非常感谢，本
回答by Mitch Wheat
In TSQL, you need to use ISrather than =when comparing with NULL:
在 TSQL 中，您需要使用IS而不是=与 比较时NULL：
SELECT * FROM table WHERE field IS NULL
回答by Nick DeVore
Try
尝试
select * from table where field IS null
回答by samjudson
You want IS NULLI believe:
你要IS NULL我相信：
SELECT * FROM table WHERE field IS NULL
