[英]Sql Case Statement Error Cannot select More Than one Column
我需要從Case語句中的SQL Select語句獲取供應商ID。 將A.SUPPLIER_ID
放入Select語句后,出現錯誤。 這個怎么做?
Select
CASE
WHEN TYPE = 1 THEN
(
SELECT A.name
from BIZZXE_V2_SCH.SUPPLIERS A
where A.SUPPLIER_ID = 30
)
ELSE
(
SELECT A.name
from BIZZXE_V2_SCH.STOCK_SUPPLIER A
where A.SUPPLIER_ID = 31
)
END name
from DUAL;
您不能將完整的查詢放入case
語句中。 但這應該有效
SELECT name
from BIZZXE_V2_SCH.SUPPLIERS
where SUPPLIER_ID = 30 and TYPE = 1
union all
SELECT name
from BIZZXE_V2_SCH.STOCK_SUPPLIER
where SUPPLIER_ID = 31 and TYPE <> 1
您應該能夠像這樣在WHERE語句中處理此問題。
SELECT A.name
FROM BIZZXE_V2_SCH.STOCK_SUPPLIER A
WHERE (A.SUPPLIER_ID = 30 AND TYPE = 1) OR
A.SUPPLIER_ID = 31
使用IF/ELSE
語句
DECLARE @type NUMBER;
SELECT TYPE INTO @type FROM DUAL; -- Make sure it always returns one row
IF @type = 1 THEN
SELECT A.name
FROM BIZZXE_V2_SCH.SUPPLIERS A
WHERE A.SUPPLIER_ID = 30;
ELSE
SELECT A.name
FROM BIZZXE_V2_SCH.STOCK_SUPPLIER A
WHERE A.SUPPLIER_ID = 31
END IF;
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