Question

我有两个问题。我想合并一个表和两列。

SELECT COUNT(IsApproved) as CountNotApproved
FROM Erp_OrderReceipt 
WHERE IsApproved = 0

和

SELECT COUNT(IsApproved) as CountApproved
FROM Erp_OrderReceipt 
WHERE IsApproved = 1

Answer 1

您可以使用条件聚合：

SELECT COUNT(case when IsApproved = 0 then 0 end) as CountNotApproved, 
       COUNT(case when IsApproved = 1 then 1 end) as CountApproved
FROM Erp_OrderReceipt;

这是有效的，因为聚合函数会忽略NULL个值。对于与条件不匹配的所有行，CASE的结果为NULL。

如果您的DBMS支持此功能，您还可以使用ANSI SQL filter子句：

SELECT COUNT(*) FILTER (where IsApproved = 0) as CountNotApproved, 
       COUNT(*) FILTER (where IsApproved = 1) as CountApproved
FROM Erp_OrderReceipt

Answer 2

您可以使用Union和group

 SELECT SUM(CountApproved) CountApproved, 
        SUM(CountNotApproved) CountNotApproved
 FROM
 (
    SELECT 
        0 as CountApproved,
        COUNT(IsApproved) as CountNotApproved
    FROM Erp_OrderReceipt where IsApproved=0 
    UNION
    SELECT 
        COUNT(IsApproved) as CountApproved,
        0 as CountNotApproved
    FROM Erp_OrderReceipt where IsApproved=1
 ) u

在两列上合并两个SQL查询

2 个答案: