Multiple tables in the where clause SQL - sql-server

Question

I have 2 tables:-
Table_1
GetID UnitID
1 1,2,3
2 4,5
3 5,6
4 6
Table_2
ID UnitID UserID
1 1 1
1 2 1
1 3 1
1 4 1
1 5 2
1 6 3
I want the 'GetID' based on 'UserID'.
Let me explain you with an example.
For e.g.
I want all the GetID where UserID is 1.
The result set should be 1 and 2. 2 is included because one of the Units of 2 has UserID 1.
I want all the GetID where UserID is 2
The result set should be 2 and 3. 2 is included because one of Units of 2 has UserID 2.
I want to achieve this.
Thank you in Advance.

Answer 1

You can try a query like this:
See live demo
select
distinct userid,getid
from Table_1 t1
join Table_2 t2
on t1.unitId+',' like '%' +cast(t2.unitid as varchar(max))+',%'
and t2.userid=1

Answer 2

The query for this will be relatively ugly, because you made the mistake of storing CSV data in the UnitID column (or maybe someone else did and you are stuck with it).
SELECT DISTINCT
t1.GetID
FROM Table_1 t1
INNER JOIN Table_2 t2
ON ',' + t1.UnitID + ',' LIKE '%,' + CONVERT(varchar(10), t2.UnitID) + ',%'
WHERE
t2.UserID = 1;
Demo
To understand the join trick being used here, for the first row of Table_1 we are comparing ,1,2,3, against other single UnitID values from Table_2, e.g. %,1,%. Hopefully it is clear that my logic would match a single UnitID value in the CSV string in any position, including the first and last.
But a much better long term approach would be to separate those CSV values across separate records. Then, in addition to requiring a much simpler query, you could take advantage of things like indices.

Answer 3

try this:
declare #Table_1 table(GetID INT, UnitId VARCHAR(10))
declare #Table_2 table(ID INT, UnitId INT,UserId INT)
INSERT INTO #Table_1
SELECT 1,'1,2,3'
union
SELECT 2,'4,5'
union
SELECT 3,'5,6'
union
SELECT 4,'6'
INSERT INTO #Table_2
SELECT 1,1,1
union
SELECT 1,2,1
union
SELECT 1,3,1
union
SELECT 1,4,1
union
SELECT 1,5,2
union
SELECT 1,6,3
declare #UserId INT = 2
DECLARE #UnitId VARCHAR(10)
SELECT #UnitId=COALESCE(#UnitId + ',', '') + CAST(UnitId AS VARCHAR(5)) from #Table_2 WHERE UserId=#UserId
select distinct t.GetId
from #Table_1 t
CROSS APPLY [dbo].[Split](UnitId,',') AS AA
CROSS APPLY [dbo].[Split](#UnitId,',') AS BB
WHERE AA.Value=BB.Value
Split Function:
CREATE FUNCTION [dbo].Split(#input AS Varchar(4000) )
RETURNS
#Result TABLE(Value BIGINT)
AS
BEGIN
DECLARE #str VARCHAR(20)
DECLARE #ind Int
IF(#input is not null)
BEGIN
SET #ind = CharIndex(',',#input)
WHILE #ind > 0
BEGIN
SET #str = SUBSTRING(#input,1,#ind-1)
SET #input = SUBSTRING(#input,#ind+1,LEN(#input)-#ind)
INSERT INTO #Result values (#str)
SET #ind = CharIndex(',',#input)
END
SET #str = #input
INSERT INTO #Result values (#str)
END
RETURN
END