Sending SQL a boolean and update a table as 1 or -1 and how to "update" an empty row for the initial values - sql

Question

I have a Songs table with a likes column that holds the number of likes users sent . Each user sends a boolean (1 or 0) through a C# app which adds to the likes column.
About my procedure:
I want to know if there is more an efficient and short way of writing the part 1 of the function?
I had to manually insert '0' instead of the NULL for the first time for the function to work. It wasn't working because the initial value for Likes column is NULL. Is there a way to affect the row for the first time when it has NULL in it?
For part 2 of the function with [Users_Likes_Songs] table, I want to update if the user send a like (true = 1) or removed it (false = 0).
How can I update this table for the first time when the users 'like' must be valued as '1', when its rows are completely empty?
I thank you very much if you can help me.
The procedure:
CREATE PROCEDURE Songs_Likes
#User_ID INT,
#SongID INT,
#Song_like BIT
AS
BEGIN
--- part 1 of the function
IF (#Song_like = 1)
BEGIN
UPDATE [Songs]
SET [Likes] = [Likes] + #Song_like
WHERE [Song_ID] = #SongID
END
IF (#Song_like = 0)
BEGIN
UPDATE [Songs]
SET [Likes] = [Likes] - 1
WHERE [Song_ID] = #SongID
END
--- part 2 of the function with the second table
UPDATE [Users_Likes_Songs]
SET [LikeSong] = #Song_like
WHERE ([UserID] = #User_ID) AND ([SongID] = #SongID)
END

Answer 1

I think that the better method would be to change your design to calculate the likes and have a table that stores the likes for each user. In simple terms, something like:
USE Sandbox;
GO
CREATE SCHEMA music;
GO
CREATE TABLE music.song (SongID int IDENTITY(1,1),
Artist nvarchar(50) NOT NULL,
Title nvarchar(50) NOT NULL,
ReleaseDate date);
CREATE TABLE music.[User] (UserID int IDENTITY(1,1),
[Login] nvarchar(128));
CREATE TABLE music.SongLike (LikeID bigint IDENTITY(1,1),
SongID int,
UserID int,
Liked bit);
CREATE UNIQUE NONCLUSTERED INDEX UserLike ON music.SongLike(SongID, UserID); --Stops multiple likes
GO
--To add a LIKE you can then have a SP like:
CREATE PROC music.AddLike #SongID int, #UserID int, #Liked bit AS
BEGIN
IF EXISTS (SELECT 1 FROM music.SongLike WHERE UserID = #UserID AND SongID = #SongID) BEGIN
UPDATE music.SongLike
SET Liked = #Liked
WHERE UserID = #UserID
AND SongID = #SongID
END ELSE BEGIN
INSERT INTO music.SongLike (SongID,
UserID,
Liked)
VALUES (#SongID, #UserID, #Liked);
END
END
GO
--And, if you want the number of likes:
CREATE VIEW music.SongLikes AS
SELECT S.Artist,
S.Title,
S.ReleaseDate,
COUNT(CASE SL.Liked WHEN 1 THEN 1 END) AS Likes
FROM music.Song S
JOIN music.SongLike SL ON S.SongID = SL.SongID
GROUP BY S.Artist,
S.Title,
S.ReleaseDate;
GO

Answer 2

For 1) this is a bit clearer, shorter and a bit more efficient.
UPDATE [Songs]
SET [Likes] = COALESCE([Likes], 0) + CASE WHEN #Song_like = 1 THEN 1
WHEN #Song_like = 0 THEN -1
ELSE 0 END
WHERE [Song_ID] = #SongID;
For the second part you can do something like this:
IF NOT EXISTS (SELECT 1
FROM [Users_Likes_Songs]
WHERE [UserID] = #User_ID
AND [SongID] = #SongID)
INSERT INTO [Users_Likes_Songs] (User_ID, SongID, [LikeSong])
VALUES (#User_ID, #SongID, #Song_like)
ELSE
UPDATE [Users_Likes_Songs]
SET [LikeSong] = #Song_like WHERE ([UserID] = #User_ID) AND ([SongID] = #SongID)

Answer 3

You can try this query in your procedure
UPDATE [songs]
SET [likes] = Isnull ([likes], 0) + ( CASE WHEN #Song_like THEN 1 ELSE -1 END)
WHERE [song_id] = #SongID