More efficient double coalesce join alternative - sql

Question

I have a procedure with a (slightly more complex) version of the below:
CREATE PROC sp_Find_ID (
#Match1 varchar(10),
#Match2 varchar(10)
) AS
DECLARE #ID int
SELECT #ID = ID
FROM Table1
WHERE Match1 = #Match1
AND Coalesce(Match2,#Match2,'') = Coalesce(#Match2,Match2,'')
SELECT #ID ID
Essentially Match1 is a mandatory match, but Match2 is both optional on the input to the procedure, and on the table being searched. The 2nd match succeeds where the input and/or the table Match2 values are null, or where they're both the same (not null) value.
My question is: Is there a more efficient (or even more readable) way of doing this?
I've used this method a few times, and I feel slightly sullied each time (subjective dirtiness admittedly).

Answer 1

Is there a more efficient (or even more readable) way of doing this?
The example you provided, using COALESCE/etc is non-sargable. You need to separate things so only what needs to be present in the query is run:
DECLARE #ID int
IF #Match2 IS NOT NULL
BEGIN
SELECT #ID = t.id
FROM TABLE1 t
WHERE t.match1 = #Match1
AND (t.match2 = #Match2 OR t.match2 IS NULL)
END
ELSE
BEGIN
SELECT #ID = t.id
FROM TABLE1 t
WHERE t.match1 = #Match1
END
SELECT #ID ID
If you want this to occur in a single SQL statement, dynamic SQL is the only real alternative. I highly recommend reading The curse and blessing of dynamic SQL before reading further:
DECLARE #SQL NVARCHAR(MAX)
SET #SQL = N' SELECT #ID = t.id
FROM TABLE1 t
WHERE t.match1 = #Match1 '
SET #SQL = #SQL + CASE
WHEN #Match2 IS NOT NULL THEN
' AND (t.match2 = #Match2 OR t.match2 IS NULL) '
ELSE
' '
END
BEGIN
EXEC sp_executesql #SQL,
N'#ID INT OUTPUT, #Match1 VARCHAR(10), #Match2 VARCHAR(10)',
#ID, #Match1, #Match2
END

Answer 2

Avoiding OR and ISNULL etc
The EXCEPT bit returns no rows if either side IS NULL
Match2 <> #Match2 means exclude non-NULL non-matching
Something like this
DROP TABLE dbo.Table1
CREATE TABLE dbo.Table1 (ID int NOT NULL, Match1 int NOT NULL, Match2 int NULL)
INSERT dbo.Table1 VALUES (1, 55, 99), (2, 55, NULL)
DECLARE #Match1 int = 55, #Match2 int
SELECT ID
FROM
(
SELECT ID FROM Table1 WHERE Match1 = #Match1
EXCEPT -- #Match2 = NULL, match both rows (99, NULL)
SELECT ID FROM Table1 WHERE Match2 <> #Match2
) foo
SET #Match2 = -1
SELECT ID
FROM
(
SELECT ID FROM Table1 WHERE Match1 = #Match1
EXCEPT -- #Match2 = -1, match ID = 2 only where Match2 IS NULL
SELECT ID FROM Table1 WHERE Match2 <> #Match2
) foo

Answer 3

Don't know if this is any more preferable.
SELECT #ID = ID
FROM Table1
WHERE Match1 = #Match1
AND ((Match2 = #Match2) OR Coalesce(Match2,#Match2) IS NULL)

Answer 4

I would have thought this should do it - providing that the #Match2 value will be NULL if it is optional.
CREATE PROC sp_Find_ID (
#Match1 varchar(10),
#Match2 varchar(10)
) AS
DECLARE #ID int
SELECT #ID = ID
FROM Table1
WHERE Match1 = #Match1
AND Match2 = IsNull(#Match2, Match2)
SELECT #ID ID

Answer 5

Seems simple to me? I must be missing something.. you dont need the Coalesce
SELECT #ID = ID
FROM Table1
WHERE Match1 = #Match1
AND (
(Match2 is null and #Match2 is null)
or
#Match2=Match2
)
SELECT #ID ID