Building dynamic where condition in SQL statement - sql

Question

I want to build custom Where condition based on stored procedure inputs, if not null then I will use them in the statement, else I will not use them.
if #Vendor_Name is not null
begin
set #where += 'Upper(vendors.VENDOR_NAME) LIKE "%"+ UPPER(#Vendor_Name) +"%"'
end
else if #Entity is not null
begin
set #where += 'AND headers.ORG_ID = #Entity'
end
select * from table_name where #where
But I get this error
An expression of non-boolean type specified in a context where a condition is expected, near 'set'.

Answer 1

Use this :
Declare #Where NVARCHAR(MAX)
...... Create your Where
DECLARE #Command NVARCHAR(MAX)
Set #Command = 'Select * From SEM.tblMeasureCatalog AS MC ' ;
If( #Where <> '' )
Set #Comand = #Command + ' Where ' + #Where
Execute SP_ExecuteSQL #Command
I tested this and it Worked

Answer 2

You cannot simply put your variable in normal SQL as you have in this line:
select * from table_name where #where;
You need to use dynamic SQL. So you might have something like:
DECLARE #SQL NVARCHAR(MAX) = 'SELECT * FROM Table_Name WHERE 1 = 1 ';
DECLARE #Params NVARCHAR(MAX) = '';
IF #Vendor_Name IS NOT NULL
BEGIN
SET #SQL += ' AND UPPER(vendors.VENDOR_NAME) LIKE ''%'' + UPPER(#VendorNameParam) + ''%''';
END
ELSE IF #Entity IS NOT NULL
BEGIN
SET #SQL += ' AND headers.ORG_ID = #EntityParam';
END;
EXECUTE SP_EXECUTESQL #SQL, N'#VendorNameParam VARCHAR(50), #EntityParam INT',
#VendorNameParam = #Vendor_Name, #EntityParam = #Entity;
I assume your actual problem is more complex and you have simplified it for this, but if all your predicates are added using IF .. ELSE IF.. ELSE IF, then you don't need dynamic SQL at all, you could just use:
IF #Vendor_Name IS NOT NULL
BEGIN
SELECT *
FROM Table_Name
WHERE UPPER(vendors.VENDOR_NAME) LIKE '%' + UPPER(#Vendor_Name) + '%';
END
ELSE IF #Entity IS NOT NULL
BEGIN
SELECT *
FROM Table_Name
WHERE headers.ORG_ID = #Entity;
END

Answer 3

old question but want to add that i just found using
where
CASE WHEN #id = 0
THEN 1
ELSE id
END
=
CASE WHEN #id = 0
THEN 1
ELSE #id
END
this is from these steps:
where id = #id
check if #id is null (or invalid) or have valid value so replace #id using case:
where id =
CASE WHEN #id is null
THEN 0
ELSE #id
END
this is will end up as
where id = 0 -- if #id is null, still affected your query
where id = #id -- if #id have valid value
because we want use this "where" clause only if have valid data then we change id too
where
CASE WHEN #id is null
THEN 0
ELSE id
END
=
CASE WHEN #id is null
THEN 0
ELSE #id
END
then will end up as
where 0 = 0 -- if #id is null and it doesn't affect your query
where id = #id -- if #id have valid value
don't forget if id is varchar, use 0 as '0'
CASE WHEN #id is null
THEN '0'
ELSE id
END
i use this in my project and working well, even i use more than 1 of this in one query. please let me know if this query costing time at larger data

Answer 4

No need to use ad-hoc query (execute SP_ExecuteSQL)
Check below logic, you can use N number of dynamic / un-sure parameters / conditions
-- flages
declare #chk_vendor bit;
declare #chk_entity bit;
-- setting off
set #chk_entity = 0;
set #chk_vendor = 0;
if #Vendor_Name is not null
begin
set #chk_vendor = 1;
end
else if #Entity is not null
begin
set #chk_entity = 1;
end
SELECT *
FROM table_name
WHERE (UPPER(vendors.VENDOR_NAME) LIKE '%' +
UPPER(#Vendor_Name) + '%' OR #chk_vendor = 0)
AND (headers.ORG_ID = #Entity OR #chk_entity = 0)
I am posting this answer as there many similar questions , remember flag will just enable or disable a condition