What is the result of print @STR ?

I think it will be empty as you are building @strqry up with a potential outcome that it will be null. When you add the to @STR you will end up with a null string and therefore no query to run.

The following is one way round the problem

@transfrmdt date,

@transtodt date,

@cid integer,

@Type char(1)

DEClare @strqry varchar(max)

DEClare @STR varchar(max)

set @strqry= 'select name from Mas_C where 1 = 1 '

If (@Type<>'')

BEGIN

SET@strqry= @strqry +' and type='''+@Type+''''

END

If (@cname<>'')

BEGIN

SET@strqry= @strqry +' and cid='''+@cid+''''

END

SET @STR =' SELECT convert(varchar (10),transdt,111)as Transdt,amt

FROM Transcation WHERE 1=1

and Transdt between convert(varchar (10),@transfrmdt,111) and convert(varchar (10),@transtodt,111) '

+@strqry

print @STR

exec(@str)

SELECT sum(Amt) as TotalAmt

FROM Transcation WHERE Transdt between convert(varchar (10),@transfrmdt,111) and convert(varchar (10),@transtodt,111)

(Edited to add)

I ran the query above (with @type and @cname as empty) and got the following:-

SELECT CONVERT(VARCHAR(10), transdt, 111) AS Transdt ,

amt

FROM Transcation

WHERE 1 = 1

AND Transdt BETWEEN CONVERT(VARCHAR(10), @transfrmdt, 111)

AND CONVERT(VARCHAR(10), @transtodt, 111)

SELECT name

FROM Mas_C

WHERE 1 = 1

I'm not sure if you wanted two separate queries, or if you wanted to have the second as a filter for name.