mysql - 简单的sql查询返回零行

Question

我的查询:

SELECT * FROM game_tbl WHERE ( `player_o` = 1 OR `player_x` = 1 ) AND ( `player_o` = NULL OR `player_x` = NULL )

game_tbl:

使用:mysql

结果为零行，我想要“game1”。好吧，我想我可以使用其他查询，但是，对于我理解正确的错误 SQL 语法很重要，谢谢大家

Answer 1

尝试使用 IS NULL 而不是 = NULL，例如:

SELECT * 
FROM game_tbl 
WHERE (`player_o` = 1 OR `player_x` = 1) AND (`player_o` IS NULL OR `player_x` IS NULL)

Here's MySQL 有关使用 NULL 值的文档。

To test for NULL, use the IS NULL and IS NOT NULL operators.

You cannot use arithmetic comparison operators such as =, <, or <> to test for NULL.