[英]IIF Function from SQL to HSQLDB
我在MS Access中有以下SQL语句-
WITH
qryAwayMatches AS (SELECT MATCHTEAM.FOOTBALLMATCHID, MATCHTEAM.TEAMID, MATCHTEAM.GAMETYPE, MATCHPROTOCOL.MATCHTEAMID, MATCHPROTOCOL.GOALNUMBER,
MATCHPROTOCOL.YELLOWCARDNUMBER, MATCHPROTOCOL.REDCARDNUMBER FROM MATCHTEAM LEFT JOIN MATCHPROTOCOL ON MATCHTEAM.ID = MATCHPROTOCOL.MATCHTEAMID WHERE (((MATCHTEAM.GAMETYPE)='Away'))),
qryHomeMatches AS (SELECT MATCHTEAM.FOOTBALLMATCHID, MATCHTEAM.TEAMID, MATCHTEAM.GAMETYPE, MATCHPROTOCOL.MATCHTEAMID, MATCHPROTOCOL.GOALNUMBER,
MATCHPROTOCOL.YELLOWCARDNUMBER, MATCHPROTOCOL.REDCARDNUMBER FROM MATCHTEAM LEFT JOIN MATCHPROTOCOL ON MATCHTEAM.ID = MATCHPROTOCOL.MATCHTEAMID WHERE (((MATCHTEAM.GAMETYPE)='Home'))),
qryMatchResult AS (SELECT qryHomeMatches.FootballMatchID, qryHomeMatches.TeamID AS HomeTeamID,
qryAwayMatches.TeamID AS AwayTeamID,
qryHomeMatches.GoalNumber>qryAwayMatches.GoalNumber AS HomeTeamWin,
qryHomeMatches.GoalNumber=qryAwayMatches.GoalNumber AS NoWin,
qryHomeMatches.GoalNumber<qryAwayMatches.GoalNumber AS AwayTeamWin
FROM qryHomeMatches INNER JOIN qryAwayMatches ON qryHomeMatches.FootballMatchID = qryAwayMatches.FootballMatchID)
SELECT Round.RoundNumber, Team.Name, **IIf([HomeTeamWin],3,IIf([NoWin],1,0)) AS Points**
FROM Round
INNER JOIN (Team INNER JOIN (RoundDetail INNER JOIN qryMatchResult ON RoundDetail.FootballMatchID = qryMatchResult.FootballMatchID) ON Team.ID = qryMatchResult.HomeTeamID) ON Round.ID = RoundDetail.RoundID;
当我尝试使用HSQLDB在Java中按按钮执行此语句时,出现以下错误:
java.sql.SQLSyntaxErrorException: user lacks privilege or object not found: IIF
我该如何解决这个问题?
从文档看来,HSQLDB不支持IIF函数,我无法在函数列表中找到它:
http://hsqldb.org/doc/2.0/guide/builtinfunctions-chapt.html#bfc_general_functions
但一个好消息是:HSQLDB支持大小写表达式:
http://hsqldb.org/doc/2.0/guide/dataaccess-chapt.html#dac_query_expression
案件
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case表达式由ANSI I SQL标准定义,并且大多数数据库都支持case表达式,而IIF函数是专有和非标准的。
您可以重写:
iif ( condition, value_if_true, value_if_false )
通过这种方式使用case表达式:
CASE WHEN condition THEN value_if_true ELSE value_if_false END
例如:
SELECT CASE WHEN col1>1 THEN 20 ELSE 50 END
FROM ....
代替
SELECT iif(col1>1,20,50)
FROM ...
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