simplify if statement with stored procedure - sql

Question

i have a following stored procedure where i am repeating similar code. all i am doing is checking the condition based on Sample id1, sampleid2, and sample id3 to follow in similar fashion. The value of 'y' goes on till about it reaches 10, so it's going to be a big 'if' condition based statements. i was trying to see if a better solution could be put in place. thanks.
#select = 'select * from tbl Sample......'
if(x = 1 and y=1)
set #where = 'where Sample.id1 >=1 and <=10'
if(x = 1 and y=2)
set #where = 'where Sample.id1 >=11 and <=20'
if(x=2 and y=1)
set #where = 'where Sample.id2 >=1 and <= 10'
if(x=2 and y=2)
set #where = 'where Sample.id2 >=11 and <=20'
if(x=3 and y=1)
set #where = 'where Sample.id3 >=1 and <=10'
if(x=3 and y=2)
set #where = 'where Sample.id3 >=11 and <=20' //increment goes on
exec(#select+#where)

Answer 1

In general, if there is no easy correlation between the values of x, y and the filtered columns id1, id2 etc, then you could move the where predicates into a table keyed by values of x and y, and then use this as a lookup to apply to your PROC. Assuming the SPROC is used heavily, the lookup table can be made permanent and indexed on your x,y input mapping columns.
CREATE TABLE dbo.WhereMappings
(
x INT,
y INT,
Predicate NVARCHAR(MAX),
CONSTRAINT PK_MyWhereMappings PRIMARY KEY(x, y)
)
INSERT INTO dbo.WhereMappings(x, y, Predicate) VALUES
(1, 1, 'Sample.id1 > 5 and Sample.id2 <= 10'),
(1, 2, 'Sample.id1 > 7 and Sample.id2 <= 15'),
(2, 1, 'Sample.id2 > 2 and Sample.id3 <= 18');
Your proc then simplifies to:
CREATE PROC MyProc(#x INT, #y INT) AS
BEGIN
DECLARE #sql NVARCHAR(MAX);
DECLARE #predicate NVARCHAR(MAX);
SELECT TOP 1 #predicate = Predicate
FROM dbo.WhereMappings WHERE x = #x AND y = #y;
-- TODO THROW if predicate not mapped
SET #sql = CONCAT('SELECT * FROM Sample WHERE ', #predicate);
EXECUTE(#sql);
END;
Re : What does this solve
Although this hasn't necessarily reduced the complexity of the original queries, it does however allow for a data-only maintenance approach to the mappings, e.g. Admin UI screens could be written to maintain (and validate! think Sql Injection) the predicate mappings, without the need for direct modification to the SPROC.
Edit
After your edit, it does appear that there is a correlation between x, y and the filtered column and range used in the idx predicates, viz x sets the column, and y sets the range between.
In that case, simply append the value of x to an id column name stub, and multiply out the value of the BETWEEN clause to y*10 - 9 to y * 10;

Answer 2

You may do something like this:
select
*
from
tbl Sample
where
(#x=1 and #y=1 and Sample.id1>=..and Sample.id1<=..) --(or you could use between)
OR (#x=1 and #y=2 and Sample.id1>=..and Sample.id1<=..)
..

Answer 3

set #select = 'select * from tbl Sample......'
set #where = 'where Sample.id'+convert(nvarchar(10),#x)+' >=....and <=...'
exec(#select+#where)

Answer 4

I would suggest to use another sql table which will have information of all these condition like shown in below screenshot.
Then use join in your sql query like.(Assume above table has name Limit
select * from tbl Sample smpl
inner join Limit lmt
on #x=lmt.x and #y=lmt.y and
(
(#x=1 and smpl.id1 >= lmt.Min_limit and smpl.id1 <=lmt.Max_limit) or
(#x=2 and smpl.id2 >= lmt.Min_limit and smpl.id2 <=lmt.Max_limit) or
(#x=3 and smpl.id3 >= lmt.Min_limit and smpl.id3 <=lmt.Max_limit)
)
In this I have tried to avoid dynamic query.

Answer 5

I usually try to find a relation between inputs and outputs and in this case I found this way:
SET #where = 'WHERE Sample.id{0} >= {1} + 1 and <= {1} + 10'
SET #where = REPLACE(#where, '{0}', CAST(x AS varchar(5)))
SET #where = REPLACE(#where, '{1}', CAST((y - 1) AS varchar(5)))

Answer 6

I think you want something like:
SET #where = 'where Sample.id' + CAST(#x AS VARCHAR(10)) + ' between ' +
CAST((#y - 1) * 10 + 1 AS VARCHAR(10)) + ' and ' +
CAST(#y * 10 AS VARCHAR(10))