Data Definition and Data Manipulation Language-DDL & DML

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About Me

Md. Selim HossainLecturer

Dept. of CSEUTTARA UNIVERSITY

House#05, Section#06,Road#15, Uttara, Dhaka-1230.

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Database Management System (DBMS)Md. Selim Hossain

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Topics for Today

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Data Definition Language (DDL)

Data Manipulation Language (DML)

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SQL statements are divided into two major

categories:

Data Definition Language (DDL) and Data Manipulation Language (DML).

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Data Definition Language (DDL)

• DDL statements are used to build and modify the structure of tables and other objects in the database.

• DDL is a sub-language of SQL used to create and manipulate objects in a database. DDL provides the following statements to manipulate the object in database:

CREATE, ALTER, DROP, TRUNCATE, RENAME

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Data Definition Language (DDL) CREATE statement (to create objects in the database):• The CREATE statement in SQL creates a

component in a relational database management system (RDBMS).

• The CREATE command is used to establish a new database, table, index, or stored procedure.

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CREATE TABLE statement• A commonly used CREATE command is the

CREATE TABLE command. The typical usage is: CREATE TABLE [table name] ( [column

definitions] ) [table parameters]

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CREATE TABLE statement• An example of statement to create a table

named employees with a few columns is:

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CREATE TABLE statement

Note: The full structure of table can be viewed with the DESC command.

DESC <TABLE_NAME>


DROP statement

• The DROP statement destroys an existing database, table, index, or view.

• A DROP statement in SQL removes a component from a relational database management system (RDBMS).

• Drop statement is used to delete an existing object from the database. It can also be used to delete any column from a table.


DROP statement

• The DROP statement is distinct from the DELETE and TRUNCATE statements, in that DELETE and TRUNCATE do not remove the table itself. For example, a DELETE statement might delete some (or all) data from a table while leaving the table itself in the database, whereas a DROP statement removes the entire table from the database.


DROP statement


DROP statement The typical usage is simply:

• For example, the command to drop a table named employees is:


ALTER statement

• The ALTER statement modifies an existing database object or, Alter statement is used to modify the structure of an existing object.

• Below alteration can be done on a table:o Addition of new columnso Deletion of existing columnso Changing the data type of columnso Changing the size of columns


ALTER statement

• The typical usage is:


ALTER statement

Note: To change the data type of a column, the column must be empty.


RENAME statement

Rename statement is used to rename an existing object from a database


RENAME statement

• The RENAME statement is used to rename a database table.


TRUNCATE statement

• The TRUNCATE statement is used to delete all data from a table. It's much faster than DELETE.



• A data manipulation language (DML) is a family of syntax elements similar to a computer programming language used for selecting, inserting, deleting and updating data in a database.


Data Manipulation Language (DML) DML also known as query language

Two classes of languages Procedural – user specifies what data is

required and how to get those data Nonprocedural – user specifies what data is

required without specifying how to get those data



• DML is a sub-language of SQL. It is used to manipulate the data stored in a table.

• DML provides the following statements for data manipulation:

INSERTUPDATEDELETE



INSERT Statement• INSERT statement is used to insert a new

record into a table.


Data Manipulation Language (DML)INSERT Statement

• Example• Consider a table 'EMP' having columns

named EMPNO, NAME, SAL and JOB. We can be used the below INSERT statement to insert a new record to it.


UPDATE Statement

• Update statement is used to update an existing record in a table.


UPDATE Statement• If the where clause of omitted, the statement

will update all the values in the particular column.


UPDATE Statement

• Note: IS NULL is used for assignment and =NULL is used to recognize.


DELETE Statement

• Delete Statement is used to delete records from a table.


DELETE Statement


DELETE Statement

• Below statement will delete all records from the table.

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Data Definition and Data Manipulation Language-DDL & DML