SQL Server Learning Drive

Introduction to Structured Query
Language (SQL)
By Techandmate.com
Learn SQL Server With US

Objectives
2
 Explore basic commands and functions of SQL
 How to use SQL for data administration (to create
tables, indexes, and views)
 How to use SQL for data manipulation (to add,
modify, delete, and retrieve data)
 How to use SQL to query a database to extract
useful information

Agenda
 What is SQL ?
 Data Types
 Constraints
 Database Relationships
 SQL Queries
 Transact- SQL Commands | DDL , DCL ,DML
 Retrieving Data
 Customizing Data
 Grouping Data
 SQL Operators
 Joining Data

Agenda continue
 Inserting , Updating and Deleting Data
 Working With Tables
 Working with Views
 Working With Constraints
 Generating Scripts
 Working with Stored Procedures
 Working with Functions

Introduction to SQL
5
 SQL stands for Structured Query Language. SQL is used to
communicate with a database. According to ANSI (American
National Standards Institute), it is the standard language for
relational database management systems
 SQL functions fit into two broad categories:
 Data definition language
 SQL includes commands to:
 Create database objects, such as tables, indexes, and
views
 Define access rights to those database objects
 Data manipulation language
 Includes commands to insert, update, delete, and retrieve
data within database tables

SQL Database Objects
 A SQL Server database has lot of objects like
 Tables
 Views
 Stored Procedures
 Functions
 Rules
 Defaults
 Cursors
 Triggers

SQL Server Data types
 Integer : Stores whole number
 Float : Stores real numbers
 Text : Stores characters
 Decimal: Stores real numbers
 Money : Stores monetary data. Supports 4 places
after decimal
 Date : Stores date and time
 Binary : Stores images and other large objects
 Miscellaneous : Different types special to SQL Server.

 A null value is an unknown
 Null value is not as zero or space.

 every value in a column or set of columns must
be unique.
 When there is not the primary key.
 Example
 no two employees can have the same phone
number

 The primary key value must be unique and not null.
 Multiple UNIQUE constraints and only one Primary
key in a Table .

 FOREIGN KEY in one table points to a PRIMARY
KEY in another table.
 prevents that invalid data form being inserted into the
foreign key column

 used to limit the value range that can be placed in a
column.
 Example :
 A column must only include integers greater than 0

 used to insert a default value into a column

 Create , Alter , Drop , Truncate
 meant to deal with the structure of the database objects (the
object itself) like tables, views, procedures and so on.
 Insert , Delete , Update , SELECT
 deal with the contents of the tables rather than the structure
of the tables
 GRANT , DENY , REVOKE
 maintain security of the database objects access and use

 adding a new database object to the database
 changing the structure of an existing database
object
 removing a database object from the database
permanently
 removing all rows from a table without logging the
individual row deletions

 retrieving data from the database by specifying
which columns and rows to be retrieved
 adding a new row (and not column) into the table
 modifying the existing data in the tabl
 removing an existing data from the table

 giving privileges to the users
 denies permissions from a security account in the
current database and prevents the security account
from inheriting the permission through its group or
role memberships
 removing privileges from the users that are
previously granted those permissions

 Retrieve data from database
SELECT * | column1 [, column2,
…….]
FROM table

 Specify a condition to limit the result
SELECT * | column1 [, column2, …….]
FROM table
[WHERE conditions]

 sort the retrieved rows by a specific column or set of
columns
SELECT * | column1 [, column2, …….]
FROM table
[WHERE conditions]
[ORDER BY column1 [, column2, ……..] ASC,
DESC]

 eliminates duplicate row values from the results
 Example : the Next Slide

 used to divide the rows in a table into smaller
groups
SELECT * | column1, group_function (column2),
…….
FROM table
[WHERE conditions]
[GROUP BY column1, ……..]
DESC]

 used to restrict the group results
SELECT * | column1, group_function (column2),
…….
FROM table
[WHERE conditions]
[GROUP BY column1, ……..]
HAVING [conditions]
DESC]

 Arithmetic operators
 Comparison operators
 Logical operators
 Set Operators
 Other operators

 addition (+)
 subtraction (-)
 multiplication (*)
 division (/).

 compare two or more values
DescriptionOperator
Equal=
Lease than<
Greater than>
Less than or equal<=
Greater than or equal>=
Not Equal<>

• Used to get a logical value (True or
False)

 combine the results of two or more queries into one
result
 UNION/ UNION ALL
 INTERSECT
 EXCEPT

EmpLacation
Egypt
Canada
Egypt
VacLocation
Egypt
Canada
France
Union
Egypt
Canada
France
Intersect
Egypt
Canada
Except
France

• Create a Single Result Set from
Multiple Queries
– Similar data types
– Same number of columns
– Same column order in select list
USE northwind
SELECT (firstname + ' ' + lastname) AS name
,city, postalcode
FROM employees
UNION
SELECT companyname, city, postalcode
FROM customers
GO

 returns only the records that have the same values
in the selected columns in both tables.
USE northwind
,city, postalcode
FROM employees
INTERSECT
FROM customers
GO

 return rows returned by the first query that are not
present in the second query
USE northwind
,city, postalcode
FROM employees
EXCEPT
FROM customers
GO

 Example 1 (without an alias name)
 Example 2 (with an alias name)
USE joindb
SELECT buyer_name, s.buyer_id, qty
FROM buyers AS b INNER JOIN sales AS s
ON b.buyer_id = s.buyer_id
GO
USE joindb
SELECT buyer_name, sales.buyer_id, qty
FROM buyers INNER JOIN sales
ON buyers.buyer_id = sales.buyer_id
GO
This slide from 2071b from Microsoft

 Introduction to Joins
 Using Inner Joins
 Using Outer Joins
 Using Cross Joins
 Joining More Than Two Tables
 Joining a Table to Itself

 Selects Specific Columns from Multiple Tables
 JOIN keyword specifies that tables are joined and
how to join them
 ON keyword specifies join condition
 Queries Two or More Tables to Produce a Result
Set
 Use primary and foreign keys as join conditions
 Use columns common to specified tables to join
tables

 return rows only when there is at least one row from
both tables that matches the join condition
SELECT <select list>
FROM table1 inner join table2
ON (table1.column1 = table2.column2)

USE joindb
FROM buyers INNER JOIN sales
GO
sales
buyer_id prod_id qty
1
1
4
3
2
3
1
5
15
5
37
11
4 2 1003
buyers
buyer_name
Adam Barr
Sean Chai
Eva Corets
Erin O’Melia
buyer_id
1
2
3
4
Result
buyer_name
Adam Barr
Adam Barr
Erin O’Melia
Eva Corets
buyer_id qty
1
1
4
3
15
5
37
11
Erin O’Melia 4 1003
Example 1

 includes all rows in the left table in the results whether or
not there are matching values on the common column in the
right table. in addition to the matching values in Both table.
: All rows from the Left table are returned
FROM table1 left outer join table2
ON (table1.column1 = table2.column2)

USE joindb
FROM buyers LEFT OUTER JOIN sales
GO
sales
1
1
4
3
2
3
1
5
15
5
37
11
4 2 1003
buyers
buyer_name
Adam Barr
Sean Chai
Eva Corets
Erin O’Melia
buyer_id
1
2
3
4
Result
buyer_name
Adam Barr
Adam Barr
Erin O’Melia
Eva Corets
buyer_id qty
1
1
4
3
15
5
37
11
Erin O’Melia 4 1003
Sean Chai NULL NULL
Example 1

 the reverse of LEFT OUTER joins
 All rows from the right table are returned
 Null values are returned for the left table any time a right
table row has no matching row in the left table.
FROM table1 right outer join table2
ON (table1.column1 =
table2.column2)

 returns all the rows from the left table , and all the
rows from the right table
 Also it returns rows in the left table that do not
have matches in the right table, or if there are
rows in right table that do not have matches in the
left table.

NameID
Some11
Some22
Some33
CountryID
Loc11
Loc22
Loc44
SELECT a.id ,b.id, a.name , b.country
FROM LeftTable as a
Full Join RightTable as b
On a.id = b.id
Full Join

 Join table with it self
SELECT a.column , b.column
FROM Table1 as a
JOIN Table1 as b
ON a.column = b.column

• I want Every Employee Name with his Manager

 return all rows from both tables
 Each row from the left table is combined with all
rows from Second Table
 the number of rows in the left table multiplied by
the number of rows in the right table.
 Table1 >> 2 rows,
 Table2 >> 5 rows,
 >>10 rows
 Example :
 Possible ways

Name
Ali
Islam
Country
Egypt
Cairo
CountryName
EgyptAli
CairoAli
EgyptIslam
CairoIslam

USE joindb
SELECT buyer_name, qty
FROM buyers
CROSS JOIN sales
GO
Result
buyer_name
Adam Barr
Adam Barr
Adam Barr
Adam Barr
qty
15
5
37
11
Adam Barr 1003
Sean Chai 15
Sean Chai 5
Sean Chai 37
Sean Chai 11
Sean Chai 1003
Eva Corets 15
... ...
sales
1
1
4
3
2
3
1
5
15
5
37
11
4 2 1003
buyers
buyer_id
1
2
3
4
buyer_name
Adam Barr
Sean Chai
Eva Corets
Erin O’Melia
Example 1

 is responsible for adding a new row into the
table
INSERT [INTO] table
[column1, column2, ………..]
VALUES (value1, value2, ………….. )

• Inserting Data without columns
name

• Inserting Data with columns name
Note: You can verify the result by write SELECT
statement.

SELECT …… <select_list>
INTO <new_table>
FROM <table_name>
[WHERE <search_condition>]

 is responsible for modifying the existing data in the
table
UPDATE <table>
SET column1 = value1 [, column2 = value2, ……]
WHERE [conditions]

 is responsible for removing an existing data from
the table
DELETE <table>
WHERE [conditions]

:
 removes all rows from a table
TRUNCATE Table <table>

 is new statement in SQL Server 2008
 INSERT, UPDATE, and DELETE in a single
statement . Based on Condition

MERGE INTO table_name table_alias
USING (table|view|sub_query) alias
ON (join condition)
WHEN MATCHED THEN
UPDATE SET
col1 = col_val1,
col2 = col2_val
WHEN NOT MATCHED THEN
INSERT (column_list)
VALUES (column_values);

 create new tables
CREATE TABLE <table_name>
(
column1 datatype ,
column2 datatype ,
...............
(

 Altering an existing table
 Using User Interface

modify existing tables
ALTER TABLE <table_name>
Add colum_name datatype
ALTER COLUMN colum_name datatype
DROP COLUMN colum_name datatype

 Disallow null , and decrease length

 Dropping an existing table

 drop existing tables
: Don’t forget to Press Refresh
DROP TABLE <table_name>

 is simply a SELECT statement that has been given
a name and stored in a database
 Restricting data access
 Making complex queries easy

CREATE VIEW <view_name>
AS <select_statement>
Create View LondonEmployees
as
SELECT EmloyeeId , LastName , FirstName
,City , Address
FROM Employees

 Any changes to View that may cause a record
disappear from the view , will raises runtime error
.
 Example :
Create view SomeOrders
as
SELECT * FROM Orders where Orders.ShipCity =
'London‘
With Check Option

 Creating tables with constraints

 Create a new Database >> New Database
 Attach Existing Database >> Attach

 removes the database entry from the instance
 closes all files associated to the database
 releases all operating system locks
 Detaching a database

 Database diagrams graphically show the structure
of the database
1. Select your database from the Databases node
in the Object Explorer.
2. Right-click the Database Diagrams folder.
3. Select the New Database Diagram

 Files with Extension (.sql )
script1.sql

:
a sequence of operations performed as a single
logical unit of work.
all of its data modifications are performed or none of
them is performed.

 Autocommit transactions
 The default for SQL Server
 Each individual DML or DDL statement is committed when it
Completes
 You do not have to specify any statements to control
transactions
 Implicit transactions
SET IMPLICIT_TRANSACTIONS ON
Each Transact-SQL statement
(INSERT,UPDATE,DELETE) execute as a
Transaction
 Explicit transactions
Starting with BEGIN TRANSACTION Statement

: The COMMIT statement.
: The ROLLBACK statement .

>> automatically Rollback
 If it prevents the successful completion of a
transaction
>> need to Check @@Error
 constraint violation (Check Constraint )

Define a location to which a transaction can return
like save point in any game
SAVE TRANSACTION <savepoint_name>
ROLLBACK TRANSACTION
<savepoint_name>

 You Can :
 Contains Statement that Perform Operations
 Accept input Parameters
 Return Status Value
 success or failure
 Return Multiple Output parameters

 They are registered (permanently stored) at the
server.
 They can have security attributes (such as
permissions).
 They can enhance the security of your
application.
 They allow modular programming.
 They are named code and so they allow
repeating execution.
 They can reduce network traffic.

 User-defined stored procedures
 System stored procedures

CREATE PROC | PROCEDURE
<procedure_name>
[@parameter data_type]
AS <sql_statement>

ALTER PROC | PROCEDURE
<procedure_name>
[@parameter data_type]
AS <sql_statement>

DROP PROC | PROCEDURE <procedure_name>

 Like functions in programming languages
 accept parameters
 perform an action
 return the result of that action as a value
 They allow modular programming.
 They allow faster execution.
 They always return a value to the calling program.

 User-defined scalar functions
 Built-in Functions

CREATE FUNCTION <function_name>
[(@parameter data_type)]
RETURNS return_data_type | table
[AS]
BEGIN
function_code
RETURN scalar_expression | select
statement
END

 specifies TABLE as a return data type
 returns a SELECT statement rather than a single
value

 Using the ALTER FUNCTION statement
ALTER FUNCTION <function_name>
[(@parameter data_type)]
RETURNS return_data_type
[AS]
BEGIN
function_code
RETURN scalar_expression
END

 a special type of stored procedure.
 Invoked automatically
 Not called directly
 DDL triggers
 DML triggers

 They can query other tables and include complex
Transact-SQL statements
 They can reference columns in other tables
 with more complex than check

 override the standard actions
CREATE TRIGGER <trigger_name> on <table
| view>
INSTEAD OF INSERT | UPDATE | DELETE
AS
BEGIN
<trigger_code>
END

 INSTEAD OF INSERT triggers
 INSTEAD OF UPDATE triggers
 INSTEAD OF DELETE triggers

Create a trigger that protects all the data in
the Course table from deletion

:
create trigger that insert new trainee when
inserting new course

 Alter and Drop statements
: Drop trigger

 This is not every thing about Transact-SQL
 This is just an introduction
 May you read :
 2071B Book (Querying MS SQL Server with Transact-SQL )
 2073A Book(Programming MS SQL Server Database)
 MSDN : http://msdn.microsoft.com/en-
us/library/aa299742(v=SQL.80).aspx
 Google

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