合并两列SQL查询

Question

我有两个查询。我想合并一个表格和两列。

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

可以使用条件汇聚了这一点：

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

这工作，因为聚合函数忽略NULL值。对于与条件不匹配的所有行，CASE的结果为NULL。

如果你的DBMS支持这一点，你也可以使用ANSI SQL filter条款：

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

Answer 2

您可以使用联盟和组对该

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