SQL Compare two tables update and set flag - sql

Question

I have two tables, the first one is called table1, the structure and contents are shown below
+--+-----+------+------+
|ID|fname|Lname |Status|
+--+-----+------+------+
|1 |Pat |Test | |
+--+-----+------+------+
|2 |Su |Test2 | |
+--+-----+------+------+
|3 |Bri |Test4 | |
+--+-----+------+------+
|4 |Mel |Gi | |
+--+-----+------+------+
|5 |Good |Record| |
+--+-----+------+------+
|6 |Tr |BL | |
+--+-----+------+------+
The second table has updates that need to be committed to table1.
+--+-------+-----+
|ID|Fname |Lname|
+--+-------+-----+
|1 |Patrick|Cool |
+--+-------+-----+
|2 |Susun |Smart|
+--+-------+-----+
|6 |True |Blood|
+--+-------+-----+
I would like to compare both tables and update table1 with the contents of table 2. (compare using ID) If any update is done on any row, i would like the status column to be marked as UPDATED. If a row exists in table1 but it doesnt exist in table2 i would like the status of that row in table1 marked as DELETE. Rows with no changes should have no status
The after the update the final output should resemble
+--+-------+------+------+
|ID|fname |Lname |Status|
+--+-------+------+------+
|1 |Patrick|Cool |UPDATE|
+--+-------+------+------+
|2 |Susun |Smart |UPDATE|
+--+-------+------+------+
|3 |Brian |Brown |DELETE|
+--+-------+------+------+
|4 |Mel |Gibson|DELETE|
+--+-------+------+------+
|5 |Good |Record||
+--+-------+------+------+
|6 |True |Blood |UPDATE|
+--+-------+------+------+
Any help will be appreciated

Answer 1

maybe try a nested query?
for the deleted updated
UPDATE table_1 SET status = "DELETED" WHERE id NOT IN (
SELECT id FROM table_2
)
for update
UPDATE table_1, table_2
SET table_1.status = "UPDATED",
table_1.fName = table_2.FName,
table_1.lName = table_2.LName
WHERE table_1.id IN (
SELECT id FROM table_1, table_2
WHERE table_1.id = table_2.id AND
(table_1.fName!= table_2.FName OR table_1.lName!=table_2.LName)
)
(edited)update with join
UPDATE table_1
SET table_1.fName = t2.FName, table_1.lName = t2.LName, table_1.status = "UPDATED"
FROM table_1 AS t1 JOIN table_2 AS t2 USING (id)
WHERE t1.fName!=t2.FName OR t1.lName!=t2.LName

Answer 2

hashbrown ->
the code above is just not showing the "DELETED" , "UPDATED" , sorry about that (:
So I'll add this code which can help
Read more in Simple-talk-> the merge statement in sql server 2008
IF OBJECT_ID ('BookInventory', 'U') IS NOT NULL
DROP TABLE dbo.BookInventory;
CREATE TABLE dbo.BookInventory -- target
(
TitleID INT NOT NULL PRIMARY KEY,
Title NVARCHAR(100) NOT NULL,
Quantity INT NOT NULL
CONSTRAINT Quantity_Default_1 DEFAULT 0
);
IF OBJECT_ID ('BookOrder', 'U') IS NOT NULL
DROP TABLE dbo.BookOrder;
CREATE TABLE dbo.BookOrder -- source
(
TitleID INT NOT NULL PRIMARY KEY,
Title NVARCHAR(100) NOT NULL,
Quantity INT NOT NULL
CONSTRAINT Quantity_Default_2 DEFAULT 0
);
INSERT BookInventory VALUES
(1, 'The Catcher in the Rye', 6),
(2, 'Pride and Prejudice', 3),
(3, 'The Great Gatsby', 0),
(5, 'Jane Eyre', 0),
(6, 'Catch 22', 0),
(8, 'Slaughterhouse Five', 4);
INSERT BookOrder VALUES
(1, 'The Catcher in the Rye', 3),
(3, 'The Great Gatsby', 0),
(4, 'Gone with the Wind', 4),
(5, 'Jane Eyre', 5),
(7, 'Age of Innocence', 8);
--1 Implementing the WHEN MATCHED Clause
MERGE BookInventory bi
USING BookOrder bo
ON bi.TitleID = bo.TitleID
WHEN MATCHED THEN
UPDATE
SET bi.Quantity = bi.Quantity + bo.Quantity;
SELECT * FROM BookInventory;
--2 Implementing the WHEN MATCHED Clause (Delete)
MERGE BookInventory bi
USING BookOrder bo
ON bi.TitleID = bo.TitleID
WHEN MATCHED AND
bi.Quantity + bo.Quantity = 0 THEN
DELETE
WHEN MATCHED THEN
UPDATE
SET bi.Quantity = bi.Quantity + bo.Quantity;
SELECT * FROM BookInventory;
--3 Implementing the WHEN NOT MATCHED [BY TARGET] Clause
MERGE BookInventory bi
USING BookOrder bo
ON bi.TitleID = bo.TitleID
WHEN MATCHED AND
bi.Quantity + bo.Quantity = 0 THEN
DELETE
WHEN MATCHED THEN
UPDATE
SET bi.Quantity = bi.Quantity + bo.Quantity
WHEN NOT MATCHED BY TARGET THEN
INSERT (TitleID, Title, Quantity)
VALUES (bo.TitleID, bo.Title,bo.Quantity);
SELECT * FROM BookInventory;
--4 Implementing the WHEN NOT MATCHED BY SOURCE Clause
MERGE BookInventory bi
USING BookOrder bo
ON bi.TitleID = bo.TitleID
WHEN MATCHED AND
bi.Quantity + bo.Quantity = 0 THEN
DELETE
WHEN MATCHED THEN
UPDATE
SET bi.Quantity = bi.Quantity + bo.Quantity
WHEN NOT MATCHED BY TARGET THEN
INSERT (TitleID, Title, Quantity)
VALUES (bo.TitleID, bo.Title,bo.Quantity)
WHEN NOT MATCHED BY SOURCE
AND bi.Quantity = 0 THEN
DELETE;
SELECT * FROM BookInventory;
--5 Implementing the OUTPUT Clause
DECLARE #MergeOutput TABLE
(
ActionType NVARCHAR(10),
DelTitleID INT,
InsTitleID INT,
DelTitle NVARCHAR(50),
InsTitle NVARCHAR(50),
DelQuantity INT,
InsQuantity INT
);
MERGE BookInventory bi
USING BookOrder bo
ON bi.TitleID = bo.TitleID
WHEN MATCHED AND
bi.Quantity + bo.Quantity = 0 THEN
DELETE
WHEN MATCHED THEN
UPDATE
SET bi.Quantity = bi.Quantity + bo.Quantity
WHEN NOT MATCHED BY TARGET THEN
INSERT (TitleID, Title, Quantity)
VALUES (bo.TitleID, bo.Title,bo.Quantity)
WHEN NOT MATCHED BY SOURCE
AND bi.Quantity = 0 THEN
DELETE
OUTPUT
$action,
DELETED.TitleID,
INSERTED.TitleID,
DELETED.Title,
INSERTED.Title,
DELETED.Quantity,
INSERTED.Quantity
INTO #MergeOutput;
SELECT * FROM BookInventory;
SELECT * FROM #MergeOutput
--where ActionType = 'UPDATE'

Answer 3

You can use the Merge Clause and OUTPUT
IF OBJECT_ID (N'dbo.Purchases', N'U') IS NOT NULL
DROP TABLE dbo.Purchases;
GO
CREATE TABLE dbo.Purchases (
ProductID int, CustomerID int, PurchaseDate datetime,
CONSTRAINT PK_PurchProdID PRIMARY KEY(ProductID,CustomerID));
GO
INSERT INTO dbo.Purchases VALUES(707, 11794, '20060821'),
(707, 15160, '20060825'),(708, 18529, '20060821'),
(711, 11794, '20060821'),(711, 19585, '20060822'),
(712, 14680, '20060825'),(712, 21524, '20060825'),
(712, 19072, '20060821'),(870, 15160, '20060823'),
(870, 11927, '20060824'),(870, 18749, '20060825');
GO
IF OBJECT_ID (N'dbo.FactBuyingHabits', N'U') IS NOT NULL
DROP TABLE dbo.FactBuyingHabits;
GO
CREATE TABLE dbo.FactBuyingHabits (
ProductID int, CustomerID int, LastPurchaseDate datetime,
CONSTRAINT PK_FactProdID PRIMARY KEY(ProductID,CustomerID));
GO
INSERT INTO dbo.FactBuyingHabits VALUES(707, 11794, '20060814'),
(707, 18178, '20060818'),(864, 14114, '20060818'),
(866, 13350, '20060818'),(866, 20201, '20060815'),
(867, 20201, '20060814'),(869, 19893, '20060815'),
(870, 17151, '20060818'),(870, 15160, '20060817'),
(871, 21717, '20060817'),(871, 21163, '20060815'),
(871, 13350, '20060815'),(873, 23381, '20060815');
GO
select * from Purchases;
select * from FactBuyingHabits;
--Now this is the Place where you do the manipulation you want
MERGE dbo.FactBuyingHabits AS Target
USING (SELECT CustomerID, ProductID, PurchaseDate FROM dbo.Purchases) AS Source
ON (Target.ProductID = Source.ProductID AND Target.CustomerID = Source.CustomerID)
WHEN MATCHED THEN
UPDATE SET Target.LastPurchaseDate = Source.PurchaseDate
WHEN NOT MATCHED BY TARGET THEN
INSERT (CustomerID, ProductID, LastPurchaseDate)
VALUES (Source.CustomerID, Source.ProductID, Source.PurchaseDate)
OUTPUT $action, Inserted.ProductId InsertedProductId,
Inserted.CustomerId InsertedCustomerId,
Inserted.LastPurchaseDate InsertedLastPurchaseDate,
Deleted.ProductId DeletedProductId,
Deleted.CustomerId DeletedCustomerId,
Deleted.LastPurchaseDate DeletedLastPurchaseDate;
select * from FactBuyingHabits;
drop table FactBuyingHabits;
drop table Purchases;