如何將兩個查詢的結果合並為一行？

Question

我有兩個查詢，每個查詢返回一個結果，即一個數字

Select Count(*) as StockCountA from Table_A where dept='AAA'

結果

StockCountA 
550

。

Select Count(*) as StockCountB from Table_B where dept='BBB'

結果

StockCountB 
450

我希望將兩個結果合並為一行記錄，即

| StockCountA | StockCountB    
| 550         | 450

Answer 1

您可以使用：

select
(Select Count(*) as StockCountA from Table_A where dept='AAA') as StockCountA,
(Select Count(*) as StockCountB from Table_B where dept='BBB') as StockCountB

說明：您可以在select語句中選擇單個值作為字段，因此可以編寫如下內容

select
  x.*,
  (select Value from Table_Y y) as ValueFromY
from
  Table_X x

這僅適用於標量查詢 ，這意味着子查詢應具有恰好1列，最多1行。 如果行數為0，則ValueFromY將返回NULL ；如果行數超過1，則查詢將失敗。

select的另一個功能（在SQL Server，MySQL和其他可能的版本中）是，您可以只選擇值，而無需完全指定表，如下所示：

Select
  3.14 as MoreOrLessPI

您可以通過編寫如下查詢來將這兩個事實結合起來，將兩個計數結合為一個結果：

Select
  (Select query that returns at most 1 row) as Result1,
  (Select another query that returns at most 1 row) as Result2

Answer 2

這應該給您期望的結果：

SELECT * FROM(
(Select Count(*) as StockCountA from Table_A where dept='AAA') StockCountA ,
(Select Count(*) as StockCountB from Table_B where dept='BBB') StockCountB
);

Answer 3

試試下面的SQL：

select (Select Count(*) as StockCountA from Table_A where dept='AAA')  StockCountA, 
       (Select Count(*) as StockCountB from Table_B where dept='BBB')  StockCountB

希望這可以幫助 ：）

Answer 4

雖然並非總是最佳做法，但可以進行交叉加入。

SELECT
COUNT(Table_A.SOME_COLUMN) as StockCountA
,COUNT(Table_B.SOME_COLUMN) as StockCountB
FROM Table_A, Table_B WHERE Table_A.dept='AAA' AND Table_B.dept='BBB'