05 qmds2005 session07

Querying and Managing Data Using SQL Server 2005
Objectives

In this session, you will learn to:
Manage databases
Manage tables

Ver. 1.0 Session 7 Slide 1 of 33

Identifying the System Databases in SQL Server 2005

SQL Server 2005 contains the following system databases:
– master: The master database that records all the
server-specific configuration information.
– tempdb: The temporary database that holds all temporary
tables and stored procedures.
– model: The model database that acts as a template or
prototype for the new databases.
– msdb: The database that handles the task of scheduling,
exception handling, etc.
– Resource: Read-only database that contains all the system
objects included in the SQL Server 2005.


Just a minute

What is the utility of the model database?

Answer:
The model database acts as a template or a prototype
for the new databases.


Creating a User-Defined Database

User-defined database:
Is stored as a set of files. These files include:
• Primary data file
• Secondary data file
• Transaction log file
Syntax:
CREATE DATABASE database_name
[ ON [ PRIMARY ] [ < filespec >]]
[ LOG ON { < filespec > [ ,...n ] } ]
< filespec > ::=
( [ NAME = logical_file_name , ]
FILENAME = 'os_file_name'
[ , SIZE = size ]
[ , MAXSIZE = { max_size | UNLIMITED } ]
[ , FILEGROWTH = growth_increment ] ) [,...n]
Let’s see how…

Just a minute

Which statement is used to create a database?

Answer:
The CREATE DATABASE statement


Creating a Table

Table:
Is created to store data
Is created by using the CREATE TABLE statement
Syntax:
CREATE TABLE
[ database_name . [ schema_name ] .]
table_name
( { <column_definition> |
<computed_column_definition> }
[ <table_constraint> ] [ ,...n ] )
[ ON { partition_scheme_name (
partition_column_name ) | filegroup
| "default" } ]
[ { TEXTIMAGE_ON { filegroup | "default" } ]
[ ; ]

Creating a Table (Contd.)

Example:
Create an EmployeeLeave table in the HumanResources
schema with the following details:
Columns Data Type Checks

EmployeeID int NOT NULL

LeaveStartDate date NOT NULL

LeaveEndDate date NOT NULL

LeaveReason varchar(100) NOT NULL

LeaveType char(2) NOT NULL

Let’s see how…


Implementing Data Integrity

Avoids data redundancy
Ensures that the data in a database is accurate, consistent,
and reliable
Is broadly classified into the following categories:
Entity integrity: Ensures that each row can be uniquely
identified by an attribute called the primary key
Domain integrity: Ensures that only a valid range of values is
allowed to be stored in a column
Referential integrity: Ensures that the values of the foreign
key match the value of the corresponding primary key
User-defined integrity: Refers to a set of rules specified by a
user, which do not belong to the entity, domain, and referential
integrity categories


Implementing Data Integrity (Contd.)

You can maintain data integrity by:
Applying constraints
Applying rules
Using user-defined types



Constraints can be applied:
By using CREATE TABLE statement
By using ALTER TABLE statement
Syntax:
CREATE TABLE table_name
(
column_name CONSTRAINT constraint_name
constraint_type [,CONSTRAINT constraint_name
constraint_type]
)



Constraints are of the following types:
Primary key constraint
Unique constraint
Foreign key constraint
Check constraint
Default constraint



Primary key constraint:
Is defined on a column or a set of columns whose values
uniquely identify all the rows in a table
Does not allow NULL values in the column
Ensures entity integrity
Syntax:
(
col_name [CONSTRAINT constraint_name PRIMARY
KEY [CLUSTERED|NONCLUSTERED]
col_name [, col_name [, col_name [, …]]]
)



Unique constraint:
Is defined to enforce uniqueness in non-primary key columns
Allows one NULL value in the column
Syntax:
(
col_name [CONSTRAINT constraint_name UNIQUE
[CLUSTERED | NONCLUSTERED]
(col_name [, col_name [, col_name [, …]]])
)



Foreign key constraint:
Is defined to remove the inconsistency in two tables when the
data in one table depends on the data in another table
Associates one or more columns (the foreign key) of a table
with an identical set of columns (a primary key column) in
another table



Syntax:
(
col_name [CONSTRAINT constraint_name FOREIGN
KEY (col_name [,
col_name [, …]])
REFERENCES table_name (column_name [,
column_name [, …]])]
(col_name [, col_name [, col_name [, …]]])
)
Let’s see how…



Check constraint:
Is defined to enforce domain integrity by restricting the values
to be inserted in a column
Can be defined on multiple columns
Is specified by using the following keywords:
IN
LIKE
BETWEEN



Syntax:
(
col_name [CONSTRAINT constraint_name] CHECK
(expression)
(col_name [, col_name [, …]])
.
)
Let’s see how…



Default constraint:
– Is defined to assign a constant value to a column
– Syntax:
(
col_name [CONSTRAINT constraint_name]
DEFAULT (constant_expression | NULL)
(col_name [, col_name [, …]])
.
)
Let’s see how…


Just a minute

Which keyword is used to specify a check constraint?

Answer:
A check constraint can be specified by using the LIKE,
IN, and BETWEEN keywords.



Rules:
Help in enforcing domain integrity for columns or user-defined
data types
Can be specified to the column or the user-defined data type
before an INSERT or UPDATE statement is issued
Are used to implement business-related restrictions or
limitations
Can be created by using the CREATE RULE statement
Syntax:
CREATE RULE rule_name AS
conditional_expression
Can be bound by using the sp_bindrule stored procedure
Let’s see how…



User-defined data types:
Are custom data types defined by the users with a custom
name
Can be created by using the CREATE TYPE statement
Syntax:
CREATE TYPE [ schema_name. ] type_name { FROM
base_type [ ( precision
[ , scale ] ) ] [ NULL | NOT NULL ] } [ ; ]
Let’s see how…


Just a minute

You want to create a rule, rule1, which allows the user to
enter any of the four values: Tea, Coffee, Soup, or Miranda
in a column. Which command should you execute?

Answer:
CREATE RULE rule1 AS @TypeRule IN ('Tea',
'Coffee', 'Soup', 'Miranda')


Creating a Partitioned Table

Flash presentation: Partitioning Tables
Partitioned table:
Is created when the table contains voluminous data
Is created to separate data into multiple physical locations
based on a range of values for a specific column
Helps in improving query performance
Can be created by:
Creating a partition function
Creating a partition scheme
Creating a table by using the partition scheme


Modifying a Table

Modify a table:
When there is a requirement to add or remove columns and
constraints
Using the ALTER TABLE statement
Syntax:
ALTER TABLE [ database_name . [ schema_name ]
. | schema_name . ]
table_name
{ ALTER COLUMN column_name
{ [ NULL | NOT NULL ]
} | [ WITH { CHECK | NOCHECK } ] ADD COLUMN
<column_definition>
{ ADD CONSTRAINT constraint_name
constraint_type
Let’s see how…


Just a minute

You are managing a large table. You want to improve the
performance of the table and want the table to be more
manageable. Which strategy can you use?

Answer:
Partition the table


Dropping a Table

Drop a table:
When a table is not required
Using the DROP TABLE statement
Syntax:
DROP TABLE [ database_name . [ schema_name ]
. ] table_name
Let’s see how…


Demo: Managing Tables

Problem Statement:
The management of AdventureWorks, Inc. has decided to
provide travel and medical reimbursements to the employees.
They want to store the details of these reimbursements in the
database. For this, you need to create a database table,
EmployeeReimbursements. The details of the tables are
shown in the following table.
Columns Data Type and Size Constraints

RimID int Primary key

EmployeeID int Foreign Key references the EmployeeID of
the Employee Table, NOT NULL
Amount money Amount>0

RimType varchar(20) RimType should be Medical, Cash, or
Local
Pending_with varchar(30) NOT NULL

How will you create the table?


Demo: Managing Tables (Contd.)

Solution:
To solve the preceding problem, you need to perform the
following tasks:
1. Write the query to create a table.
2. Execute the statement to verify the result.


Summary

In this session, you learned that:
A database is a repository of information that contains data in
an organized way.
The master database records all the server-specific
configuration information, including authorized users,
databases, system configuration settings, and remote servers.
The tempdb database is a temporary database that holds all
temporary tables and stored procedures.
The model database acts as a template or a prototype for the
new databases.
The msdb database supports the SQL Server Agent. The SQL
Server Agent includes features that schedule periodic activities
of the SQL Server.
The Resource database is a read-only database that contains
all the system objects that are included with SQL Server 2005.


Summary (Contd.)

The user-defined databases are created by the users to store
data for client-server applications.
A database consists of the following types of files:
• Primary data file
• Secondary data file
• Transaction log file
– A database must consist of a primary data file and one
transaction log file.
– The CREATE DATABASE statement is used to create a
database, which also includes determining the name of the
database, the size of the database, and the files used to store
data in the database.
– Tables are used to store data.


Summary (Contd.)

Tables are used to store data.
The CREATE TABLE statement is used to create a table.
Data integrity is enforced to keep the data in a database
accurate, consistent, and reliable. It is broadly classified into
the following categories:
• Entity integrity: Ensures that each row can be uniquely identified
by an attribute called the primary key.
• Domain integrity: Ensures that only a valid range of values is
allowed to be stored in a column.
• Referential integrity: Ensures that the values of the foreign key
match the value of the corresponding primary key.
• User-defined integrity: Refers to a set of rules specified by a
user, which do not belong to the entity, domain, and referential
integrity categories.


Summary (Contd.)

Constraints define rules that must be followed to maintain
consistency and correctness of data.
A primary key constraint is defined on a column or a set of
columns whose values uniquely identify rows in a table.
The unique constraint is used to enforce uniqueness on non-
primary key columns.
A foreign key constraint associates one or more columns of a
table (the foreign key) with an identical set of columns on
which a primary key constraint has been defined (a primary
key column in another table).
A check constraint enforces domain integrity by restricting the
values to be inserted in a column. The IN, LIKE, and
BETWEEN keywords are used to define the check constraint.


Summary (Contd.)

A default constraint can be used to assign a constant value to
a column, and the user need not insert values for such a
column.
A rule provides a mechanism for enforcing domain integrity for
columns or user-defined data types.
User-defined data types are custom data types defined by the
users with a custom name.
A partitioned table is created to manage the data and improve
the query performance.
The ALTER TABLE statement is used to modify a table.
The DROP TABLE statement is used to delete a table.


05 qmds2005 session07

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