考虑下面的数据库表:
id | is_visible
________|_______________
1 | true
2 | false
3 | -- i.e. null
我想选择所有具有is_visible = null的行。我尝试了以下查询:
SELECT * FROM table_name WHERE is_visible IS NULL;
SELECT * FROM tab WHERE is_visible = null; -- 0 results
SELECT * FROM tab WHERE is_visible <> true; -- only fields with false value
SELECT * FROM tab WHERE is_visible <> false; -- only fields with true
我在postgresql和sql server中尝试过它
如何选择具有is_visible = null的行?