Case Statement in where clase in sql server 2014 - sql-server

Question

I am creating a store procedure and in which am I stuck in a problem. I want to query two columns based on condition. If parameter is numeric then query to one column and if it is nonnumeric then query to other column. Following is the procedure.
$
declare #result AS varchar(50)
DECLARE #peopleId AS varchar(50)
if('232332' NOT LIKE '%[^0-9]%')
BEGIN
SET #result='Numeric'
PRINT #result
END
ELSE
BEGIN
set #result='nonNumeric'
print #result
END
select isnull(class.grade,'') as grade,ISNULL(class.room,'') as room,student.prefix as prefix,student.student_id as student_id,(person.first_name+' '+person.last_name) as name,
person.dob as dob,person.people_id as people_id,quit_on,
case when student.student_status='30' then
N'พักการเรียน'
when student.student_status='31' then
N'น.ร.ไปเรียนโครงการฯ'
else ''
end
as quit_reason from school_student student
inner join people_person person on student.person_id=person.id
left join school_classroom_students classStudent on classStudent.student_id=student.id
left join school_classroom class on class.id =classStudent.classroom_id
where student.student_status in('30','31') and student.system_status = 'DC' and student.school_id=#schoolId
AND case
WHEN
#result='nonNumeric' then-- this should execure
person.people_id=#peopleId
else---- this should work
person.first_name+' '+ person.last_name LIKE '%'+#peopleId+'%'
Please help me out on this

Answer 1

Why would use use a separate variable? You can do:
WHEN (person.people_id = try_convert(int, #peopleId) or
try_convert(int, #peopleId) is null and
person.first_name + ' ' + person.last_name LIKE '%' + #peopleId + '%'
)
I question why you are passing a value that is used for both a string and numeric comparison. If I were using a variable, I would do:
declare #personid int;
declare #personname varchar(255);
if #peopleid not like '%[^0-9]%'
set #personname = #peopleid;
else
set #personid = convert(int, #peopleid);
where (personid = #personid or
person.first_name + ' ' + person.last_name LIKE '%' + #personname + '%'
)
The code just seems easier to follow.

Answer 2

Since SQL Server doesn't treat results of CASE expressions as booleans, you have to add an extra comparison. The way to do that is like this:
WHERE 1 = CASE WHEN x THEN 1 WHEN y THEN 0 ELSE 1 END
Conditions which result in rows being included in the result must evaluate to 1, and conditions which don't, must evaluate to something other than 1 (like 0). So the whole CASE expression returns either 0 or 1, and that is compared to 1.
In your code, it would look like this:
AND 1 = case
WHEN
#result='nonNumeric' then case when person.person_id = #peopleId then 1 else 0 end
else when person.first_name+' '+person.last_name LIKE '%'+#peopleId+'%' then 1 else 0 end
end
I added the END.

Answer 3

Just do like that
DECLARE #IsNumeric INT = NULL
DECLARE #IsNotNumeric INT = NULL
DECLARE #peopleId Varchar(50)
SET #peopleId = '123'
IF ISNUMERIC(#peopleId) = 1
BEGIN
SET #IsNumeric = 1
END
ELSE
BEGIN
SET #IsNotNumeric = 1
END
IN WHERE Condition Just Check
AND (#IsNumeric IS NULL OR CONVERT(VARCHAR(500),person.people_id)=#peopleId)
AND (#IsNotNumeric IS NULL OR person.first_name+' '+ person.last_name LIKE '%'+#peopleId+'%')