Servlet deleting updating searching a row from table
The output from the statement shows that the expected rows from the input stream are corrected, inserted, or deleted. Because the additional search conditions specified in the ON clause are not used for matching the source and target data, they can be misapplied.-- MERGE statement with the join conditions specified correctly. Employee Name LIKE 'S%' THEN INSERT(Employee ID, Employee Name) VALUES(S. The following example demonstrates how incorrect results can occur. Employee Name WHEN NOT MATCHED BY SOURCE THEN DELETE OUTPUT $action, Inserted.*, Deleted.*; ROLLBACK TRAN; GO The search conditions used to match the source and target rows and the additional search conditions used to filter rows from either the source or target must be specified correctly to ensure that correct results are obtained. As stated earlier, the WHEN clauses specify the actions to take based on the results of the ON clause and any additional search criteria specified in the WHEN clauses.In many cases, the search conditions specified in the ON clause produces the required input stream.USE tempdb; GO BEGIN TRAN; MERGE Target AS T USING Source AS S ON (T. The search condition for matching the source and target tables and the additional search condition for filtering rows are both specified in the ON clause. We recommend following these guidelines: Suppose you have a Fact Buying Habits table in a data warehouse database that tracks the last date each customer bought a specific product. Because the additional search condition is not required to determine source and target matching, the insert and delete actions are applied to all input rows. Employee Name LIKE 'S%' ) WHEN NOT MATCHED BY TARGET THEN INSERT(Employee ID, Employee Name) VALUES(S. A second table, Purchases, in an OLTP database records purchases during a given week. Order Qty The following example uses MERGE to insert, update, or delete rows in a target table based on differences with the source data. Source(Employee ID, Employee Name) Values(104, 'Steve'); GO The following table lists the possible join types and indicates when each type is implemented by the query optimizer.The table also shows the resulting input stream for the example source and target tables when the search criteria for matching the source and target data is The example input stream results show that the input stream results depend on the combination of WHEN clauses.
For those rows, we update Fact Buying Habits with the date recorded for those purchases in Purchases by using the WHEN MATCHED THEN clause. In effect, the filtering condition -- MERGE statement with join conditions that produce unexpected results. Each week, you want to add rows of products that specific customers never bought before from the Purchases table to the Fact Buying Habits table. Consider a small company with five departments, each with a department manager. USE tempdb; GO BEGIN TRAN; MERGE Target AS T USING Source AS S ON (T. For rows of customers buying products they have already bought before, you simply want to update the date of purchase in the Fact Buying Habits table. Order Date = @Order Date GROUP BY Product ID) AS source (Product ID, Order Qty) ON (target. The company decides to re-organize its departments. Manager) WHEN NOT MATCHED BY SOURCE THEN DELETE OUTPUT $action, inserted. Performance on MERGE statements improves when UNIQUE indexes are created on the join key, so clustered indexes are created by creating a PRIMARY KEY constraint on the USE Adventure Works2008R2; GO IF OBJECT_ID (N'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. Product Inventory AS target USING (SELECT Product ID, SUM(Order Qty) FROM Sales. Departments_delta', N'U') IS NOT NULL DROP TABLE dbo. Departments_delta (Dept ID tinyint NOT NULL PRIMARY KEY, Dept Name nvarchar(30), Manager nvarchar(50)); GO INSERT INTO dbo. Fact Buying Habits', N'U') IS NOT NULL DROP TABLE dbo. Fact Buying Habits ( Product ID int, Customer ID int, Last Purchase Date datetime, CONSTRAINT PK_Fact Prod ID PRIMARY KEY(Product ID, Customer ID)); GO INSERT INTO dbo. Departments_delta VALUES (1, 'Human Resources', 'Margheim'), (2, 'Sales', 'Erickson'), (3 , 'Accounting', 'Varkey'),(4, 'Purchasing', 'Barber'), (6, 'Production', 'Jones'), (7, 'Customer Relations', 'Smith'); GO dd. These insert and update operations can be performed in a single statement using MERGE. Purchase Date) OUTPUT $action, Inserted.*, Deleted.*; table is updated by subtracting the number of orders placed each day for each product. To implement the re-organization results in the target table dbo. Departments (Dept ID tinyint NOT NULL PRIMARY KEY, Dept Name nvarchar(30), Manager nvarchar(50)); GO INSERT INTO dbo. Dept Name WHEN NOT MATCHED THEN INSERT (Dept ID, Dept Name, Manager) VALUES (dd. The following example first creates tables and loads them with some sample data. Purchases ( Product ID int, Customer ID int, Purchase Date datetime, CONSTRAINT PK_Purch Prod ID PRIMARY KEY(Product ID, Customer ID)); GO INSERT INTO dbo. Purchase Date WHEN NOT MATCHED BY TARGET THEN INSERT (Customer ID, Product ID, Last Purchase Date) VALUES (Source. If the number of orders for a product causes the product's inventory to drop to 0 or below, the row for that product is deleted from the USE Adventure Works2008R2; GO IF OBJECT_ID (N'Production.usp_Update Inventory', N'P') IS NOT NULL DROP PROCEDURE Production.usp_Update Inventory; GO CREATE PROCEDURE Production.usp_Update Inventory @Order Date datetime AS MERGE Production. Departments, the MERGE statement must implement the following changes: USE Adventure Works2008R2; GO IF OBJECT_ID (N'dbo. Departments VALUES (1, 'Human Resources', 'Margheim'),(2, 'Sales', 'Byham'), (3, 'Finance', 'Gill'),(4, 'Purchasing', 'Barber'), (5, 'Manufacturing', 'Brewer'); USE Adventure Works2008R2; GO IF OBJECT_ID (N'dbo. We insert all other rows into Fact Buying Habits by using the WHEN NOT MATCHED THEN clause. Fact Buying Habits AS Target USING (SELECT Customer ID, Product ID, Purchase Date FROM dbo. i created a program which has three classes, my program is inserting, updating, deleting, fetching records from database, and my code is working perfectly for me, but i created this for console: Here is my three classes: Emp Db now what i want is i create a from in html, for these employee records and i have three buttons on the same page (ie. and okay, i assign names to my three buttons, how my servlet will know which button is pressed and which function needs to invoke..?? Any request which hits servlet, will be processed by get() or post() which is depends on your form submit method.To illustrate, consider the following example source and target tables and data. Target(Employee ID int, Employee Name varchar(10), CONSTRAINT Target_PK PRIMARY KEY(Employee ID)); CREATE TABLE dbo.Source(Employee ID int, Employee Name varchar(10), CONSTRAINT Source_PK PRIMARY KEY(Employee ID)); GO INSERT dbo.