How to use the AND in a variable in the WHERE clause - sql

Question

I'm trying to use AND operator in a variable and use it in the WHERE clause. I'm trying to do this without using Dynamic SQL. i.e without assigning the whole query to a variable.
DECLARE #v_Criteria varchar(500)
DECLARE #jobtype varchar(500) = 'test Job'
IF #inparam ='Report1'
BEGIN
SET #v_Criteria= ''
END
ELSE IF #inparam='Report2'
BEGIN
SET #v_Criteria= ' AND InvoiceValue IS NOT NULL'
END
SELECT *
FROM tblJobs
WHERE JobID NOT IN (63,87,469)
AND JobType LIKE '%' + #jobtype + '%'
+ #v_Criteria
I used + operator before the #v_Criteria and then I get no results. If I use & opertor before #v_Criteria, I get a error. Any help would be greatly appreciated

Answer 1

You can't append a "string" to a query and it become part of the code. It's still just a string. Essentially you're trying to do Dynamic SQL, but then say you don't want Dynamic SQL?
One option is to build the logic for both cases in SQL...
SELECT *
FROM tblJobs
WHERE JobID NOT IN (63,87,469)
AND JobType LIKE '%' + #jobtype + '%'
AND (
(#inparam ='Report1')
OR
(#inparam ='Report2' AND InvoiceValue IS NOT NULL)
)
This means that the query planner has to cope with both cases all the time. One plan to solve both cases. That saves you typing, but can mean that you get a poor execution plan and waste resources or execution time.
To get around that you need two queries...
IF (#inparam = 'Report1')
BEGIN
SELECT *
FROM tblJobs
WHERE JobID NOT IN (63,87,469)
AND JobType LIKE '%' + #jobtype + '%'
END
ELSE IF (#inparam = 'Report2')
BEGIN
SELECT *
FROM tblJobs
WHERE JobID NOT IN (63,87,469)
AND JobType LIKE '%' + #jobtype + '%'
AND InvoiceValue IS NOT NULL
END
Or just use Dynamic SQL...
SET #sql= 'SELECT *
FROM tblJobs
WHERE JobID NOT IN (63,87,469)
AND JobType LIKE ''%''' + #jobtype + '%''' + #v_Criteria
EXEC sp_executesql #sql
Or...
SET #sql= 'SELECT *
FROM tblJobs
WHERE JobID NOT IN (63,87,469)
AND JobType LIKE ''%'' + #jobtype_param + ''%''' + #v_Criteria
EXEC sp_executesql
#sql,
N'#jobtype_param varchar(500)',
#jobtype_param = #jobtype
(The benefit here is that you won't make a new cached query plan for every #jopbtype. Instead it makes a parameterised query plan and re-uses it.)
EDIT:
Basically what you're investigating is Dynamic Search.
If it ever gets more complex than this example, I strongly recommend reading this article : http://www.sommarskog.se/dyn-search.html
It's complicated, and in depth, and you'll learn a lot of valuable lessons.

Answer 2

Before adding " AND " if you check if #v_Criteria is not empty string then you will not get any error.
So split AND from for example " AND InvoiceValue IS NOT NULL"
Then add AND or not according to the value of the #v_Criteria

Answer 3

What about this solution?
DECLARE #v_Criteria varchar(500)
DECLARE #jobtype varchar(500) = 'test Job'
IF #inparam ='Report1'
BEGIN
SET #v_Criteria= ''
END
ELSE IF #inparam='Report2'
BEGIN
SET #v_Criteria= ' AND InvoiceValue IS NOT NULL'
END
SELECT *
FROM tblJobs
WHERE JobID NOT IN (63,87,469)
AND JobType LIKE '%' + #jobtype + '%'
AND ISNULL(InvoiceValue, '') NOT LIKE CASE
WHEN #inparam = 'Report2'
THEN ''
ELSE 'SOMEIMPOSSIBLEVALUE'
END