Merge data between two tables using split compare - sql-server

Question

I have two tables and i need to compare data and update one table records. Please let me know how this can be done. This is the scenario
Proj1 Table
This is the first table where data needs to be synchronized
ID Text reqId
1 R1|R2 12
2 R2|R3 12
3 R3|R5|R2 12
Proj2 Table
This is the table where data updates are taking place
ID Text Active reqId
3 R1 1 12
4 R3 1 12
5 R4 1 12
I need to take each record from Proj1, use a split function then for each text in split, compare Text field between both these tables result should be similar to below. We are syncing data in Proj2 to similar to Proj1.
ID Text Active reqId
3 R1 1 12 (Ignore as it exists in both tables)
4 R3 1 12 (Ignore as it exists in both tables)
5 R4 0 12 (Update to inactive as it does not exist Proj1 table but exists in )
6 R2 1 12 (Insert as it does not exist in Proj2 table, insert only once)
7 R5 1 12 (Insert as it does not exist in Proj2 table, insert only once)

Answer 1

If you are using SQL Server 2008 or later, you could use a MERGE statement, like this:
/*
CREATE TABLE Proj1 (
ID INT PRIMARY KEY,
Text VARCHAR(100) NOT NULL,
reqId INT NOT NULL
)
INSERT INTO Proj1 VALUES (1,'R1|R2',12)
INSERT INTO Proj1 VALUES (2,'R2|R3',12)
INSERT INTO Proj1 VALUES (3,'R3|R5|R2',12)
CREATE TABLE Proj2 (
ID INT IDENTITY PRIMARY KEY,
Text VARCHAR(100) NOT NULL,
Active BIT NOT NULL,
reqId INT NOT NULL
)
SET IDENTITY_INSERT Proj2 ON
INSERT INTO Proj2 (ID, Text, Active, reqId) VALUES (3,'R1',1,12)
INSERT INTO Proj2 (ID, Text, Active, reqId) VALUES (4,'R3',1,12)
INSERT INTO Proj2 (ID, Text, Active, reqId) VALUES (5,'R4',1,12)
SET IDENTITY_INSERT Proj2 OFF
*/
GO
CREATE FUNCTION dbo.Split(#String VARCHAR(1000),#Separator CHAR(1))
RETURNS #Result TABLE (
Position INT IDENTITY PRIMARY KEY,
Value VARCHAR(1000)
) AS
BEGIN
DECLARE #Pos INT, #Prev INT
SET #Prev=0
WHILE 1=1 BEGIN
SET #Pos=CHARINDEX(#Separator,#String,#Prev+1)
IF #Pos=0 BREAK
INSERT INTO #Result (Value) VALUES (SUBSTRING(#String,#Prev+1,#Pos-#Prev-1))
SET #Prev=#Pos
END
INSERT INTO #Result (Value) VALUES (SUBSTRING(#String,#Prev+1,LEN(#String)))
RETURN
END
GO
MERGE INTO dbo.Proj2 p2
USING (
SELECT DISTINCT reqId, Value FROM dbo.Proj1 p1
CROSS APPLY dbo.Split(Text,'|') s
) x
ON p2.Text=x.Value AND p2.reqId=x.reqId
WHEN NOT MATCHED THEN INSERT VALUES (Value,1,reqid)
WHEN NOT MATCHED BY SOURCE THEN UPDATE SET Active=0
WHEN MATCHED AND Active=0 THEN UPDATE SET Active=1;
SELECT * FROM dbo.Proj2
Later edit: I added the third WHEN clause in the MERGE statement, to handle the case when the row is already present, but without the Active flag (although this case does not appear in the sample data).

Answer 2

You can also handle this without a MERGE statement, like this:
INSERT INTO Proj2
SELECT Value,1,reqid
FROM (
SELECT DISTINCT reqId, Value FROM dbo.Proj1 p1
CROSS APPLY dbo.Split(Text,'|') s
) x
WHERE NOT EXISTS (
SELECT *
FROM Proj2 p2
WHERE p2.Text=x.Value AND p2.reqId=x.reqId
)
UPDATE Proj2 SET Active=0
FROM Proj2 p2
WHERE NOT EXISTS (
SELECT *
FROM (
SELECT DISTINCT reqId, Value FROM dbo.Proj1 p1
CROSS APPLY dbo.Split(Text,'|') s
) x
WHERE p2.Text=x.Value AND p2.reqId=x.reqId
)
UPDATE Proj2 SET Active=1
FROM Proj2 p2
INNER JOIN (
SELECT DISTINCT reqId, Value FROM dbo.Proj1 p1
CROSS APPLY dbo.Split(Text,'|') s
) x ON p2.Text=x.Value AND p2.reqId=x.reqId
WHERE p2.Active=0
(I used the Split function mentioned in the other answer)