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Module 6:

Modifying Data in Tables

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Module 6: Modifying Data in Tables

Inserting Data into Tables

Deleting Data from Tables

Updating Data in Tables

Overview of Transactions

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Lesson 1: Inserting Data into Tables

INSERT Fundamentals

INSERT Statement Definitions

INSERT Statement Examples

Inserting Values into Identity Columns

INSERT and the OUTPUT Clause

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INSERT Fundamentals

INSERT [INTO] table_or_view [(column_list)] data_values

The INSERT statement adds one or more new rows toa table

INSERT inserts data_values as one or more rows intothe specified table_or_view

column_listis a list of column names used to specifythe columns for which data is supplied

INSERT Syntax:

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INSERT Statement Definitions

INSERT INTO MyTable (PriKey, Description)SELECT ForeignKey, DescriptionFROM SomeView

CREATE PROCEDURE dbo.SomeProcedureINSERT dbo.SomeTableEXECUTE SomeProcedure

INSERT TOP (#) INTO SomeTableASELECT SomeColumnX, SomeColumnYFROM SomeTableB

INSERT using SELECT

INSERT using EXECUTE

INSERT using TOP

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INSERT Statement Examples

Using a Simple INSERT Statement

INSERT INTO Production.UnitMeasureVALUES (N'F2', N'Square Feet', GETDATE());

INSERT INTO Production.UnitMeasureVALUES (N'F2', N'Square Feet', GETDATE()),(N'Y2', N'Square Yards', GETDATE());

Inserting Multiple Rows of Data

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Inserting Values into Identity Columns

CREATE TABLE dbo.T1 ( column_1 intIDENTITY, column_2 VARCHAR(30));GO

INSERT T1 VALUES ('Row #1');INSERT T1 (column_2) VALUES ('Row #2');GOSET IDENTITY_INSERT T1 ON;GOINSERT INTO T1 (column_1,column_2)

VALUES (-99, 'Explicit identityvalue');

GOSELECT column_1, column_2FROM T1;

column_listand VALUES must be used to insert valuesinto an identity column, and the SETIDENTITY_INSERT option must be ON for the table

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INSERT and the OUTPUT Clause

Using OUTPUT in an INSERT statement returns informationfrom each row affected by the INSERT statement

INSERT SomeTableOUTPUT dml_select_list INTO

(@table_variable | output_table) (column_list)

DECLARE @MyTableVar table( ScrapReasonID smallint,Name varchar(50),

ModifiedDate datetime);INSERT Production.ScrapReason

OUTPUT INSERTED.ScrapReasonID, INSERTED.Name,INSERTED.ModifiedDate

INTO @MyTableVarVALUES (N'Operator error', GETDATE());

Example Query:

Syntax:

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Demonstration: Inserting Data into Tables

In this demonstration, you will see how to:

Insert a Single Row into a Table

Insert Multiple Rows into a Table

Insert Values into Identity Columns

Use the OUTPUT Clause with the INSERT Statement

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Lesson 2: Deleting Data from Tables

DELETE Fundamentals

DELETE Statement Definitions

Defining and Using the TRUNCATE Statement

TRUNCATE versus DELETE

DELETE and the OUTPUT Clause

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DELETE Fundamentals

DELETE table_or_view

FROM table_sources

WHERE search_condition

The DELETE statement removes one or more rows in atable or view

DELETE removes rows from the table_or_viewparameter that meet thesearch condition

table_sources can be used to specify additional tablesor views that can be used by the WHERE clause

DELETE Syntax:

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DELETE Statement Definitions

DELETE FROM SomeTable;

DELETE FROM SomeTableWHERE SomeColumn IN

(Subquery Definition);

DELETE TOP (#) PERCENTFROM SomeTable;

DELETE with no WHERE clause

DELETE using a Subquery

DELETE using TOP

DELETE FROM Sales.SalesPerson;

DELETE FROM

Sales.SalesPersonQuotaHistoryWHERE SalesPersonID IN(SELECT SalesPersonIDFROM Sales.SalesPersonWHERE SalesYTD >

2500000.00);

DELETE TOP (2.5) PERCENTFROMProduction.ProductInventory;

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Defining and Using the TRUNCATE Statement

TRUNCATE TABLE HumanResources.JobCandidate;

TRUNCATE TABLE[ { database_name.[ schema_name ]. | schema_name . } ]table_name

[ ; ]

You cannot use TRUNCATE TABLE on tables thatare referenced by a FOREIGN KEY constraint

TRUNCATE TABLE Syntax

TRUNCATE TABLE Example

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TRUNCATE versus DELETE

Fewer locks are typically used

Zero pages are left in the table

Less transaction log space is used

TRUNCATE TABLE has the following advantages overDELETE:

DELETE FROM Sales.SalesPerson;

TRUNCATE TABLE Sales.SalesPerson;

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DELETE and the OUTPUT Clause

Using OUTPUT in a DELETE statement removes a row from atable and returns the deleted values to a result set

DELETE SomeTableOUTPUT column_list

DELETE Production.CultureOUTPUT DELETED.*;

Example Query:

Syntax:

CultureID Name ModifiedDate---------------------------------------Ar Arabic 1998-06-01En English 1998-06-01

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Demonstration: Deleting Data from Tables

In this demonstration, you will see how to:

Delete Rows from a Table

Truncate a Table

Delete Rows Based on Other Tables

Use the OUTPUT Clause with the DELETE Statement

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UPDATE Fundamentals

UPDATE table_or_view

SET column_name = expression

FROM table_sources

WHERE search_condition

The UPDATE statement changes data values in one,

many, or all rows of a table

An UPDATE statement referencing a table or view canchange the data in only one base table at a time

UPDATE has three major clauses:

SET comma-separated list of columns to be updated

FROM supplies values for the SET clause

WHERE specifies a search condition for the SET clause

UPDATE Syntax:

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UPDATE Statement Definitions

UPDATE SomeTableSET Column = Value

UPDATE SomeTableSET Column = ValueWHERE SearchExpression

Simple UPDATE Statement

UPDATE with a WHERE clause

UPDATE Sales.SalesPersonSET Bonus = 6000;

UPDATE Production.ProductSET Color = NMetallic RedWHERE Name LIKE NRoad-250%

AND Color = NRed;

UPDATE Sales.SalesPerson

SET Bonus = Bonus * 2;

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Updating with Information from Another Table

UPDATE SomeTableSET Column = ValueFROM SomeSubquery

UPDATE using a Subquery

UPDATE Sales.SalesPersonSET SalesYTD = SalesYTD + SubTotal

FROM Sales.SalesPerson AS spJOIN Sales.SalesOrderHeader AS soON sp.BusinessEntityID = so.SalesPersonIDAND so.OrderDate = (SELECT MAX(OrderDate)

FROM Sales.SalesOrderHeaderWHERE SalesPersonID =

sp.BusinessEntityID);

SalesYTD--------------677558.46534557045.0459

BeforeSalesYTD--------------721382.4884593234.5123

After

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UPDATE and the OUTPUT Clause

Using OUTPUT in an UPDATE statement returns informationfrom each row affected by the UPDATE statement

UPDATE SomeTableOUTPUT dml_select_list FROM table_sourceWHERE search_condition

DECLARE @NewTableVar table ( Dollars money );UPDATE Sales.SalesPersonSET Bonus = 10000OUTPUT INSERTED.Bonus INTO @NewTableVar;

SELECT DollarsFROM @NewTableVar;

Syntax:

Dollars--------10000.0010000.00...(17 row(s) affected)

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Demonstration: Updating Data in Tables

In this demonstration, you will see how to:

Update Rows in a Table

Update Rows Based on Other Tables

Use the OUTPUT Clause with the UPDATE Statement

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Lesson 4: Overview of Transactions

Transaction Fundamentals

Transactions and the Database Engine

Basic Transaction Statement Definitions

What are Transaction Isolation Levels?

Using Nested Transactions

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Transaction Fundamentals

A Transaction:

Is a sequence of operations performed as a singlelogical unit of work

Exhibits the four ACID Properties

Atomicity must be an atomic unit of work

Consistency - must leave all data in a consistent state

Isolation - must be isolated from the modifications madeby any other concurrent transactions

Durability persists even after system failure

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Transactions and the Database Engine

The Database Engine provides:

Locking facilities that preserve transaction isolation

Transaction Isolation Levels control when locks aretaken and how long they are held

Logging facilities that ensure transaction durability

Write-ahead log (WAL) guarantees no datamodifications are written before they are logged

Checkpoints write records to a data file and contain listsof all active transactions

Transaction management features that enforcetransaction atomicity and consistency

Transactions must be successfully completed or theirmodifications are undone

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Basic Transaction Statement Definitions

BEGIN { TRAN | TRANSACTION } [

Transaction_name | @tran_name_variable ]

COMMIT { TRAN | TRANSACTION } [transaction_name | @tran_name_variable ]

BEGIN TRANSACTION

COMMIT TRANSACTION

BEGIN TRAN T1;UPDATE table1 ...;

COMMIT TRAN T1;

ROLLBACK { TRAN | TRANSACTION } [transaction_name | @tran_name_variable |savepoint_name | @savepoint_variable ]

ROLLBACK TRANSACTION

ROLLBACK TRAN T1;

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What are Transaction Isolation Levels?

Transaction Isolation Levels control Whether locks are taken when data is read

How long read locks are held

How a read operation referencing rows acts

Choosing a transaction isolation level does not affectthe locks acquired to protect data modifications

SET TRANSACTION ISOLATION LEVEL ;

Syntax

The levels are READ UNCOMMITTED, READCOMMITTED, REPEATABLE READ, SNAPSHOT, andSERIALIZABLE

Demonstration: Setting Transaction Isolation

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Demonstration: Setting Transaction IsolationLevels

In this demonstration, you will see how to:

Set a Transaction Isolation Level

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CREATE TABLE TestTrans(Cola INT PRIMARY KEY,Colb CHAR(3) NOT NULL);

GOCREATE PROCEDURE TransProc @PriKey INT, @CharCol CHAR(3) ASBEGIN TRANSACTION InProcINSERT INTO TestTrans VALUES (@PriKey, @CharCol)

INSERT INTO TestTrans VALUES (@PriKey + 1, @CharCol)COMMIT TRANSACTION InProc;GOBEGIN TRANSACTION OutOfProc; /* Starts a transaction */GOEXEC TransProc 1, 'aaa';GOROLLBACK TRANSACTION OutOfProc; /* Rolls back the outer

transaction */GOEXECUTE TransProc 3,'bbb';GOSELECT * FROM TestTrans;GO

Using Nested Transactions

Explicit transactions can be nested to support

transactions in stored procedures

Cola Colb------------1 bb2 bb

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Demonstration: Using Nested Transactions

In this demonstration, you will see how to:

Create a Nested Transaction

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Lab: Modifying Data

Exercise 1: Inserting Data into Tables

Exercise 2: Deleting Data from Tables

Exercise 3: Updating Data in Tables

Exercise 4: Working with Transactions

Logon information

Virtual machine NY-SQL-01User name Administrator

Password Pa$$w0rd

Estimated time: 60 minutes

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Lab Scenario

You are a database developer at Adventure Works. You havebeen asked by the senior database administrator to add,

delete, and change rows on several tables in theAdventureWorks2008 database. You must be sure to followthe specifications that the senior database administrator hasprovided you closely so you do not insert incorrect data intothe tables, change data unnecessarily, or delete vital companydata.

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Lab Review

Why are values for column names listed in the same orderas columns on the table when using the INSERT

statement?

How can we verify that rows have been deleted after usingthe DELETE statement?

How can we write an UPDATE statement to ensure that all

rows of a table are affected?

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Module Review and Takeaways

Review Questions

Best Practices