SQL commands

DML & DCL command
Submitted by –
Pragya Singh
Class – BSc I.T. 4th semester

Content -
SQL
Introduction of DML and DCL
Statement of DML and DCL
Multiple type question

Structure Query Language(SQL)
Structure Query Language(SQL) is a database query
language used for storing and managing data in Relational
DBMS. SQL was the first commercial language
introduced for E.F Codd's Relational model of database.
Types of SQL statements –
1. DML (data manipulation language)
2. DDL (data definition language)
3. DCL (data control language)
4.TCL (transaction control language)

Introduction of DML
DML is short name of Data Manipulation Language which
deals with data manipulation and includes most common
SQL statements such SELECT, INSERT, UPDATE,
DELETE, etc., and it is used to store, modify, retrieve,
delete and update data in a database.
SELECT - retrieve data from a database
INSERT - insert data into a table
UPDATE - updates existing data within a table
DELETE - Delete all records from a database table

Select command is used to view the records from the table.
To view all the columns and all the rows ‘*’can be specified
with the select statement. The name of the table is required
while specifying the select.
Syntax :-
 Select * from <tablename>;
E.G.
“Sql> select * from student;”
Output:-
Select Command:-
ROLLNO NAME MARKS ADDR
101 ABC 75 LINK ROAD
102 XYZ 80 JM ROAD
103 PQR 67 N7

Cont…
Select statement is very flexible. If user needs to view
only certain fields or columns, then by specifying those
names of the columns in the form of list, user can view the
required output.
 The general form is as follows:
Select column1, column2, column3…… column n from <tablename>;
e.g., SQL> select rollno, name, marks from student;
Output:-
ROLLNO NAME MARKS
101 ABC 75
102 XYZ 80
103 PQR 67
3 rows selected.

Cont…
To select particular row ‘where clause is used. This clause
allows user to put the condition. The rows or columns which
satisfy the condition will be displayed.
 Syntax:-
Select<column1><column2><column3> from <tablename> where condition;
e.g., SQL> select * from student where marks=80;
102 XYZ 80 JM ROAD

Insert Command:-
After creating table successfully, records can be entered.
The insert command is used to put the records into the
table.
Syntax :-
Insert into <table name> values (value1, value2, value3…);
The list of values means the values given one by one for
each of the attribute or may not be for some of the
attributes. The values which are number can written as it
is but values which are characters and date types are
specified in ‘ ‘ i.e. In single quotation marks.
E.g., Insert into student values(101,’abc’,75,’Link road’);

Cont…
The above statement allows user to enter one by one record by
putting the values along with insert command. To enter
multiple values continuously one by one we can specify the
general command which can be afterwards run by giving the ‘ /
‘.
e.g., SQL> insert into student values(&rollno,’&studname’,&marks,’&addr’);
 After giving this command the following output will come:
 Enter value for rollno:101
 Enter value for name:xyz
 Enter value for marks: 80
 Enter value for addr: JM road

Cont…
 Old 1: insert into student values(&rollno,’&studname’,&marks,’&addr’);
 New 1: insert into student values(102,’xyz’,80,’JM road’);
1 row created
Roll no Studname marks addr
102 xyz 80 JM road

Update Command:-
 The tables can be updated using the set clause. Either all rows will be updated or modified or
selected rows can be updated using the where clause. The set clause is used to define the
modifications of a particular column.
 The syntax of update command is:
 Update<table name>set <columnname>=<expression>,<columnname>=<expression >;
 SQL> update student set marks= 85;
 3 rows updated.
 SQL> select * from student;
 Output:-
102 XYZ 85 JM ROAD
103 PQR 85 N7

Cont…
 Update Command – specifies the rows to be changed using where clause and new fata using set
keyword.
 Ex-
 Update student set sname =‘PQR’ where Roll NO = 101;
101 PQR 85 LINK ROAD
102 XYZ 85 JM ROAD
103 PQR 85 N7

Delete Command:-
 The delete operation can be performed on the table to remove or delete the particular records or
even all records.
 Syntax:-
 Delete from student where addr =N7;
 1 row deleted
 SQL> select * from student;
102 XYZ 80 JM ROAD
Output

Cont…
 To delete all records from the table the following command is used.
 SQL> delete from student;
 3 rows deleted.

Introduction to DCL
DCL stands for Data Control Language.
DCL is used to control user access in a database.
This command is related to the security issues.
Using DCL command, it allows or restricts the user from
accessing data in database schema.
DCL commands are as follows,
1. GRANT
2. REVOKE
It is used to grant or revoke access permissions from any
database user.

Grant command
GRANT command gives user's access privileges to the
database.
This command allows specified users to perform specific
tasks.
 Syntax:
GRANT <privilege list>
ON <relation name or view name>
TO <user/role list>;
Example : GRANT Command
 GRANT ALL ON employee
TO ABC;
[WITH GRANT OPTION]
 In the above example, user 'ABC' has been given permission to view and modify the records in the
'employee' table.

Revoke command
REVOKE command is used to cancel previously granted or
denied permissions.
This command withdraw access privileges given with the
GRANT command.
It takes back permissions from user.
 Syntax:
REVOKE <privilege list>
ON <relation name or view name>
FROM <user name>;
Example : REVOKE Command
 REVOKE UPDATE
ON employee
FROM ABC;

MCQ
1.The language used application programs to request data from the DBMS is referred to as __________
a) DML
b) DDL
c) Query language
d) All of the Mentioned
 Answer:a
Explanation: Data Manipulation Language (DML) statements are used for managing data in
database. DML commands are not auto-committed. It means changes made by DML command are
not permanent to database, it can be rolled back.
2. Which of the following keyword is used with Data Control Language (DCL) statements?
a) SELECT
b) INSERT
c) DELETE
d) GRANT
 Answer:d
Explanation: GRANT is the keyword which is used with Data Control Language statements

Cont…
3.Which of the following keyword is used with Data Control Language (DCL) statements?
a) SELECT
b) INSERT
c) DELETE
d) GRANT
 Answer:d
Explanation: GRANT is the keyword which is used with Data Control Language statements.
4. Which of the following is not included in DML (Data Manipulation Language)
a) INSERT
b) UPDATE
c) DELETE
d) CREATE
 Answer:d
Explanation: The CREATE TABLE statement is used to create a table in a database. Tables are
organized into rows and columns; and each table must have a name.

References
 Fundamental of Database System
Elmasri . Navathe
 Database System Concept
Henry F.koth
https://www.geeksforgeeks.org/sql-ddl-dml-dcl-tcl-commands/ on 28th March 2019
https://www.w3schools.in/mysql/ddl-dml-dcl/ on 28th March 2019

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