拆分公式函数及应用

/*

功能： 拆分公式函数

示例: select * from F_Hr_SplitFormula('a=[X] and b=[Y]') order by ID

历史：

2012-06-28 Chelen 创建

*/

create function F_Hr_SplitFormula

(

@Formula nvarchar(4000)

)

returns

@T table

(

ID int identity(1,1),

Param nvarchar(4000)

)

as

begin

declare @Posit int = 0

while CHARINDEX('[', @Formula) > 0 and CHARINDEX(']', @Formula) > 0

begin

set @Posit = CHARINDEX('[', @Formula)

insert into @T(Param) values (Substring(@Formula, 1, @Posit -1)) -- 将"["前的字符串插入到临明表

set @Formula = SUBSTRING(@Formula, @Posit, LEN(@Formula)) -- 截断"["前的字符串

--

select @Posit = CHARINDEX(']', @Formula)

if @Posit <> 0

begin

insert into @T(Param) values (Substring(@Formula, 1, @Posit)) -- 将"["和"]"间字符串(即参数)插入到临明表

set @Formula = SUBSTRING(@Formula, @Posit + 1, LEN(@Formula)) -- 截断"]"前的字符串

end

end

if @Formula <> ''

begin

insert into @T(Param) values (@Formula) --将剩余的字符串插入到临明表

end

return

end

【示例】

if OBJECT_ID('Tempdb..#Param') is not null

drop table #Param

create table #Param(ID int identity(1,1), ParamName nvarchar(50), ParamValue nvarchar(50))

insert into #Param(ParamName, ParamValue) values('语文', '80' )

insert into #Param(ParamName, ParamValue) values('数学', '95' )

insert into #Param(ParamName, ParamValue) values('英语', '90' )

declare @Formula nvarchar(4000) = '(case when [语文]+[数学]+[英语] > 270 then ''优'' when [语文]+[数学]+[英语]<180 then ''不合格'' else ''合格'' end)'

--拆分后的数据集

select * from F_Hr_SplitFormula(@Formula) f order by f.ID

select @Formula = (case when f.ID=1 then '' else @Formula end) + (case when p.ParamValue is not null then p.ParamValue else f.Param end)

from F_Hr_SplitFormula(@Formula) f

left join #Param p on '[' + p.ParamName + ']' = f.Param

order by f.ID

-- 替换后结果

select @Formula

-- 执行结果

Execute('Select ' + @Formula)

drop table #Param