TSQL: Multiple IF conditions in a stored procedure - tsql

Question

Hope I can get suggestions.
I created a stored procedure, but it is not working as intended. Basically if a value exists in a table then it will just select it, else it will insert rows to that table.
TABLE_A -- This is where I need to check if the code exists
CODE
LETTER
GREEEN
A
YELLOW
B
TABLE_B -- I use this table to get letters, there are only 2 groups.
GROUP
LETTERS
1
A
1
B
2
C
This is the stored procedure I made
CREATE PROCEDURE GET_CODE
DECLARE
#CODE VARCHAR(5) = 'RED'
,#GROUP INT = '1'
AS
BEGIN
DECLARE
#GROUPID dbo.UniqueID
,#COUNT = (SELECT count(Code) from TABLE_A where [Code] = #CODE)
/** Get letters **/
IF #GROUP = '1'
begin
insert into #GROUPID
select LETTERS from TABLE B
where GROUP = #GROUP
end
else IF #GROUP = '2'
begin
insert into #GROUPID
select LETTERS from TABLE B
where GROUP = #GROUP
end
/** if not exists insert, else go to next step **/
IF #COUNT = 0
begin
insert into TABLE_A VALUES
select
#CODE
,LETTERS
FROM #GROUPid
end
/** select where #code **/
SELECT * FROM TABLE_A where CODE = #CODE
END
Works well if the code exist, but if the code does not exist, it does not insert to TABLE_A

Answer 1

You're sproc is never going to insert into TABLE_A because you did not tell it to. You are inserting into the variable #GROUPID.
This will create a temporary table (note the #) and populate it with a row
DROP TABLE IF EXISTS #table_a
CREATE TABLE #table_a (code NVARCHAR(10), groupID INT)
INSERT INTO #table_a (code, groupID) VALUES
('Green', 2)
SELECT *
FROM #table_a
code groupID
---------------
Green 2
If we then do what you're attempting (outside of a stored procedure for now):
DECLARE #code NVARCHAR(10) = 'Red', #groupID INT = 1
IF NOT EXISTS (SELECT 1 FROM #table_a WHERE #code = code AND groupID = #groupID)
BEGIN
INSERT INTO #table_a (code, groupID) VALUES
(#code, #groupID)
END
SELECT *
FROM #table_a
WHERE code = #code
AND groupID = #groupID
code groupID
---------------
Red 1
First we declare some variables, and give them values.
Then we look to see if the values exist in the table using NOT EXISTS.
If that returns true we INSERT those values into #table_a.
Since we now know that they will exist (they either did already, or we just inserted them) we can then just select those values.
If we do the same thing again, but this time with existing values we can see it doesn't insert them again:
SET #code = 'Red'
SET #groupID = 1
IF NOT EXISTS (SELECT 1 FROM #table_a WHERE #code = code AND groupID = #groupID)
BEGIN
INSERT INTO #table_a (code, groupID) VALUES
(#code, #groupID)
END
SELECT *
FROM #table_a
WHERE code = #code
AND groupID = #groupID
code groupID
Red 1