SQL DB2/400 中的 if-else 语句
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If-else statement in DB2/400
提问by ehh
I am trying to run an SQL that contains if-else statement in AS400 but it doesn't work. I am creating a View using i Series Navigator in order to run it.
我正在尝试在 AS400 中运行包含 if-else 语句的 SQL，但它不起作用。我正在使用 i Series Navigator 创建一个视图以运行它。
SELECT IF FIELD1 IS NOT NULL THEN 'AAA' ELSE 'BBB' END IF
FROM LIB.TABLE1
The error I am getting is:
我得到的错误是：
SQL State: 42601
Vendor Code: -199
Message: [SQL0199] Keyword IS not expected. Valid tokens: , FROM INTO. Cause . .
I tried without writing is null but instead
我试过不写是空的，而是
SELECT IF FIELD1 ='' THEN 'AAA' ELSE 'BBB' END IF
FROM LIB.TABLE1
then I get the following error:
然后我收到以下错误：
SQL State: 42601
Vendor Code: -104
Message: [SQL0104] Token = was not valid. Valid tokens: , FROM INTO. Cause . . . . . : A syntax error was detected at token =. Token = is not a
回答by Lukasz Szozda
Use CASEexpression instead:
改用CASE表达式：
SELECT CASE WHEN FIELD1 IS NOT NULL THEN 'AAA' ELSE 'BBB' END
FROM LIB.TABLE1;
IFis control-flow construct:
IF是控制流结构：
IF condition THEN
SELECT ...
ELSE
SELECT ...
END IF
回答by GuestPGM
SELECT ABC, DEF,
CASE WHEN (substring(GHI,1,4)) IS 'SOTH' THEN 'J' ELSE 'N' END as SOTH
WHERE ABC like 'ABC%'
GROUP BY ABC,DEF,GHI
