Download Database Languages

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A DBMS must provide appropriate languages
and interfaces for each category of users to
express database queries and updates.
Database Languages are used to create and
maintain database on computer.
There are large numbers of database
languages like Oracle, MySQL, MS Access,
dBase, FoxPro etc.
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SQL statements commonly used in Oracle
and MS Access can be categorized as
 Data Definition Language (DDL)
 Data Control Language (DCL)
 Data Manipulation Language (DML).
It is a language that allows the users to define
data and their relationship to other types of
data.
 It is mainly used to create files, databases, data
dictionary and tables within databases.
 It is also used to specify the structure of each
table, set of associated values with each
attribute, integrity constraints, security and
authorization information for each table and
physical storage structure of each table on disk.
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Create
Alter
Drop
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Syntax:
 Create table table_name(attribute1 data
type,….attribute n data type);
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Example:
 Create table student(id number, name
varchar2(10),emailid varchar2(10));
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Syntax:
 Alter table table_name add(attribute datatype);
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Example:
 Alter table student add(phno number);
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Syntax:
 Alter table table_name drop(attribute);
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Example:
 Alter table student drop(phno);
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Syntax:
 Drop table_name;
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Example:
 Drop student;
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Create
Select
Update
Insert
Delete
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It is a language that provides a set of
operations to support the basic data
manipulation operations on the data held in
the databases.
It allows users to insert, update, delete and
retrieve data from the database.
The part of DML that involves data retrieval is
called a query language.
SQL > Create Table Cust(cname varchar2(15),cid
number(5),caddr char(10), caccno number(5),cacctype
varchar2(10),cbalance float,
Primarykey(cid),unique(cname),unique(caccno),check(cbalance>=
1000));
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SQL> desc cust;
Name
Null?
Type
----------------------------------------- -------- ---------------------------CNAME
VARCHAR2(15)
CID
NOT NULL
NUMBER(5)
CADDR
CHAR(10)
CACCNO
NUMBER(5)
CACCTYPE
VARCHAR2(10)
CBALANCE
FLOAT(126)
SQL> select * from cust;
CNAME
CID CADDR
CACCNO CACCTYPE CBALANCE
--------------- ---------- ---------- ---------- ---------- ----------------------------------Anusha
1 Chennai
1001
savings
15000
Shriram
2 Pondy
1002
savings
25000
Chamundi
3
Salem
1003
fd
36200
Madhan
4 Salem
1004
checkings
5000
Subha
5 Trichy
1005
checkings
10000
Jayashree
6
Pondy
1006
fd
15000
Sridharan
7 Kanchi
1007
fd
22000
7 rows selected.
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SQL>update cust set caccno=1111 where cname='Chamundi';
1 row updated
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SQL> select * from cust;
CNAME
CID CADDR
CACCNO
CACCTYPE
CBALANCE
--------------- ---------- ---------- ---------- ---------- -------------------------------------Anusha
1
Chennai
1001
savings
15000
Shriram
2
Pondy
1002
savings
25000
Chamundi
3
Salem
1111
fd
36200
Madhan
4
Salem
1004
checkings
5000
4 rows selected.
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SQL> insert into cust
values('Anitha',01,'Chennai',1001,'savings',150
00);
1 row created.
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SQL> insert into cust
values('Shriram',02,'Pondy',1002,'savings',250
00);
1 row created.
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SQL>delete from cust where cacctype='fd';
3 row deleted
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SQL> select * from cust;
CNAME
CID CADDR
CACCNO CACCTYPE CBALANCE
--------------- ---------- ---------- ---------- ---------- -----------------------------------Anusha
1
Chennai
1001 savings
15000
Shriram
2
Pondy
1002 savings
25000
Madhan
4
Salem
1004 checkings
5000
Subha
5
Trichy
1005 checkings
10000
4 rows selected.
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Grant
Revoke
DCL statements control access to data and the
database using statements such as GRANT and
REVOKE.
 A privilege can either be granted to a User with
the help of GRANT statement.
 The privileges assigned can be SELECT, ALTER,
DELETE, EXECUTE, INSERT, INDEX etc.
 In addition to granting of privileges, you can also
revoke (taken back) it by using REVOKE
command.
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Grant < database_priv [database_priv…..] >
to <user_name> identified by <password>
[,<password…..];
Grant <object_priv> | All on <object> to
<user | public> [ With Grant Option ];
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Revoke <database_priv> from <user [, user
] >;
Revoke <object_priv> on <object> from <
user | public >;
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In practice, the data definition and data
manipulation languages are not two separate
languages.
Instead they simply form parts of a single
database language such as Structured Query
Language (SQL).
SQL represents combination of DDL and
DML, as well as statements for constraints
specification and schema evaluation.