Question

SELECT
        (SELECT COUNT(*) FROM table1) AS count1 WHERE date='2019-06-12',
        (SELECT COUNT(*) FROM table2) AS count2 WHERE date='2019-06-12'

为什么该语句在“，”或附近引起语法错误？

Answer 1

需要在子查询中添加where clause

SELECT
       (SELECT COUNT(*) FROM table1 WHERE date='2019-06-12') AS count1 ,
       (SELECT COUNT(*) FROM table2 WHERE date='2019-06-12') AS count2

Answer 2

尝试一下-

SELECT
(SELECT COUNT(*) FROM table1 WHERE date='2019-06-12')  AS count1 ,
(SELECT COUNT(*) FROM table2 WHERE date='2019-06-12') AS count2

Answer 3

让我们重写该语句，用简单的值替换括号中的SELECT：

SELECT
        1 AS count1 WHERE date='2019-06-12',
        2 AS count2 WHERE date='2019-06-12'

现在很容易看到，直到逗号为止，您都有一个有效的SQL查询，但是您要追加要选择的其他值，这是无效的。

我假设您要在子查询中包含WHERE：

SELECT
        (SELECT COUNT(*) FROM table1 WHERE date='2019-06-12') AS count1,
        (SELECT COUNT(*) FROM table2 WHERE date='2019-06-12') AS count2

PostgreSQL-为什么此语句导致语法错误？

3 个答案: