NULL 谓词

null 值测试。

语法

value_expression IS [ NOT ] NULL

参数

示例

列名称：

=> SELECT date_key FROM date_dimension WHERE date_key IS NOT NULL;
 date_key
----------
        1
      366
     1462
     1097
        2
        3
        6
        7
        8
...

函数：

=> SELECT MAX(household_id) IS NULL FROM customer_dimension;
 ?column?
----------
 f
(1 row)

字面量：

=> SELECT 'a' IS NOT NULL;
 ?column?
----------
 t
(1 row)