UDF to evaluate a condition using select statement

Question

Here is a UDF function requirement:

CREATE FUNCTION [dbo].[ConditionEvaluation]

(@condEquation VARCHAR(MAX),
@condParameters VARCHAR(MAX
)
RETURNS bit
AS

The values of @condEquation and @condParameters are

• Example 1: @condEquation = (C01 & C02) and @condParameters =10
• Example 2: @condEquation = ((C01 & C02) | C3) and @condParameters =101

so for every C series condition in @condEquation there will be corresponding 0 or 1 values are provided in the second parameter ie @condParameters .

I want to evaluate the above condition as ...

• Example 1: select (1 & 0)
• Example 2: select ((1 & 0) | 0)

Parameter @condEquation might contain any number of Cs in the equation. But there will be corresponding number of bits in the parameter2.

I am utilizing the condition evaluation capability of SQL Select statement here, and want to return the evaluated result as 0 or 1.

How to do that using a UDF?

Answer 1

In order to accomplish this, I had to make 2 functions:

create function [dbo].[f_test1](@CondEquation varchar(50))
returns bit
as
begin
declare @result bit
;with a as
(
select replace(replace(replace(@CondEquation, '(',''), ')',''), ' ','') n
),
b as
(
select n, 1 rn from a
union all
select stuff(n, patindex('%&%', n) - 1, 3 , case when substring(n, patindex('%&%', n) - 1, 3) like '%0%' then 0 else 1 end), rn+1
from b
where patindex('%&%', n)> 0
), c as
(
select n from (
select n, row_number() over (order by rn desc) rn2 from b
) a where rn2 = 1
), d as
(
select n, 1 rn from c
union all
select stuff(n, patindex('%|%', n) - 1, 3 , case when substring(n, patindex('%|%', n) - 1, 3) like '%1%' then 1 else 0 end), rn+1
from d
where patindex('%|%', n)> 0
), e as
(
select n from (
select n, row_number() over (order by rn desc) rn2 from d
) a where rn2 = 1
)
select @result=n from e
return @result
end
go

create function [dbo].[f_test2](@CondEquation varchar(max), @condparameters varchar(max))
returns bit
as
begin
declare @result bit

declare @i int = 1
while @i <= len(@condparameters)
begin
set @CondEquation = replace(@CondEquation, 'c' + right(@i+100, 2), substring(@condparameters, @i, 1))
set @i += 1
end

declare @returnvalue bit
;with a as
(
select @CondEquation a, 1 rn
union all
select stuff(a.a, z.a-z.b+1, z.b+1,[dbo].[f_test1](substring(a.a, z.a-z.b+1, z.b+1)) ), rn+1  from
a cross apply(
select patindex('%_)%', a.a) a, charindex('(', reverse(left(a.a, patindex('%_)%', a.a)))) b
where a.a like '%)%'
) z
), b as
(
select a, row_number() over (order by rn desc) rn from a
)
select @returnvalue = [dbo].[f_test1](a) from b where rn = 1

return @returnvalue
end
go

You can test the function with this like

select dbo.[f_test2]('((C01 & C02) | C03)', '110')

Note it is important that you use the correct format of the parameters. You can't write C3 instead of C03. I surgest you go back and evaluate your old questions for correct answers.

Answer 2

    CREATE FUNCTION [dbo].[ConditionEvaluation] 

(@condEquation VARCHAR(MAX), 
@condParameters VARCHAR(MAX) 
) 
RETURNS bit 
AS 
BEGIN

declare @len int=len(@condParameters)
declare @val varchar(100)
declare @i int=1
declare @Sindex int=0
declare @op bit
set @condEquation=replace(replace(@condEquation,' ',','),')',',)')

while(@i<=@len )
begin
set @val=SUBSTRING (@condParameters,@i,1)
set @Sindex =CHARINDEX ('C',@condEquation)
set @condEquation=stuff(@condEquation,@Sindex ,charindex(',',@condEquation)-2 ,@val)
set @i=@i+1
end

set @condEquation= 'select @OP1'+replace(@condEquation,',','')+' as output1'


execute sp_executesql @condEquation,N'@OP1 int OUTPUT',@OP1=@OP OUTPUT

return @OP

END