SQL自定义函数的应用

/**************************************************************************
函数名:GetClassName(@ClassID,@ClassType)
参数:@ClassID 类别的ID号，@ClassType,类别的种类 0:语言1:总分类，2：大类别，3：子类别 ,4:国家5:省份6:市县
返回：@ClassName类别的名称 nvarchar(100)
POWER BY ADPOST
create time : 2004年3月24日 14:16:16
*************************************************************************/
CREATE FUNCTION GetClassName(@ClassID as int, @ClassType as int)
RETURNS nvarchar(100) as
begin
 declare @ClassName as nvarchar(100)
 set @ClassName = ''
 if(@ClassType = 0)
 begin
  SELECT @ClassName = LngName FROM LXBIZ_Language WHERE (LngTypeID = @ClassID)
 end
 if(@ClassType = 1)
 begin
  SELECT @ClassName = CategoryName FROM LXBIZ_Category WHERE (CategoryID = @ClassID)
 end
 if(@ClassType = 2)
 begin
  SELECT @ClassName = ClassName FROM LXBIZ_BigClass WHERE (ClassID = @ClassID)
 end
 if(@ClassType = 3)
 begin
  SELECT @ClassName = SubClassName FROM LXBIZ_SubClass WHERE (SubClassID = @ClassID)
 end
 if(@ClassType = 4)
 begin
  SELECT @ClassName = CountryName FROM LXBIZ_Country WHERE (CountryID = @ClassID)
 end
 if(@ClassType = 5)
 begin
  SELECT @ClassName = ProvinceName FROM LXBIZ_Province WHERE (ProvinceID = @ClassID)
 end
 if(@ClassType = 6)
 begin
  SELECT @ClassName = CityName FROM LXBIZ_City WHERE (CityID = @ClassID)
 end
 return @ClassName
end

SQL自定义函数在SQL查询中的应用:

我帖一个我自定义的SQL视图给大家看一下

SELECT dbo.LXBIZ_AccoutInfo.AccoutID, dbo.LXBIZ_AccoutInfo.AccoutName,
      dbo.LXBIZ_AccoutInfo.AccoutPassWord, dbo.LXBIZ_AccoutInfo.SafeQuestion,
      dbo.LXBIZ_AccoutInfo.SafeAnswer, dbo.LXBIZ_AccoutInfo.AccoutEmail,
      dbo.LXBIZ_AccoutInfo.AccoutFlag, dbo.LXBIZ_AccoutInfo.AccoutLevel,
      dbo.LXBIZ_AccoutInfo.AccountExpireTime, dbo.LXBIZ_AccoutInfo.AccountMoney,
      dbo.LXBIZ_AccoutInfo.LoginCount, dbo.LXBIZ_AccoutInfo.LastLoginIP,
      dbo.LXBIZ_AccoutInfo.LastLoginTime, dbo.LXBIZ_AccoutInfo.RegTime,
      dbo.LXBIZ_EnterpriseInfo.EnterpriseID, dbo.LXBIZ_EnterpriseInfo.CompanyFileUrl,
      dbo.LXBIZ_EnterpriseInfo.ClassID,
      dbo.GetClassName(dbo.LXBIZ_EnterpriseInfo.ClassID, 2) AS ClassName,
      dbo.LXBIZ_EnterpriseInfo.ModeTypeID, dbo.LXBIZ_EnterpriseInfo.SellKeyword,
      dbo.LXBIZ_EnterpriseInfo.BuyKeyWord, dbo.LXBIZ_EnterpriseInfo.CompanyName,
      dbo.LXBIZ_EnterpriseInfo.CountryID,
      dbo.GetClassName(dbo.LXBIZ_EnterpriseInfo.CountryID, 4) AS CountryName,
      dbo.LXBIZ_EnterpriseInfo.ProvinceID, dbo.LXBIZ_EnterpriseInfo.CityID,
      dbo.LXBIZ_EnterpriseInfo.CompanyAddress, dbo.LXBIZ_EnterpriseInfo.CompanyUrl,
      dbo.LXBIZ_EnterpriseInfo.ContactName, dbo.LXBIZ_EnterpriseInfo.JobTitle,
      dbo.LXBIZ_EnterpriseInfo.ContactSex, dbo.LXBIZ_EnterpriseInfo.ContactTel,
      dbo.LXBIZ_EnterpriseInfo.ContactFax, dbo.LXBIZ_EnterpriseInfo.ContactMobile,
      dbo.LXBIZ_EnterpriseInfo.PostCode, dbo.LXBIZ_EnterpriseInfo.BankName,
      dbo.LXBIZ_EnterpriseInfo.BankNumber, dbo.LXBIZ_EnterpriseInfo.Turnover,
      dbo.LXBIZ_EnterpriseInfo.EmployersNum, dbo.LXBIZ_EnterpriseInfo.CompnayLICD,
      dbo.LXBIZ_EnterpriseInfo.CompanyHits,
      dbo.GetClassName(dbo.LXBIZ_EnterpriseInfo.LngTypeID, 0) AS LngName, <这是取出语言类别的名称,调用以上定义的自定义函数>
      dbo.LXBIZ_EnterpriseInfo.IssueTime, dbo.LXBIZ_EnterpriseInfo.Corporate
FROM dbo.LXBIZ_EnterpriseInfo INNER JOIN
      dbo.LXBIZ_AccoutInfo ON
      dbo.LXBIZ_EnterpriseInfo.AccoutID = dbo.LXBIZ_AccoutInfo.AccoutID

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