Data Definition Language(DDL) Commands in RDBMS

DDL QUERIES:

             1.CREATE COMMAND:

                    Syntax:

                                 Create table tablename (column element fieldname column description);

                    It is used to create a new table.

            2.ALTER COMMAND:

                  Syntax:

                                Alter table tablename add on modify(column name datatypes size);

                 It is used for adding the values and also for modifying the table.

           3.SELECT COMMAND:

                 Syntax:

                               Select * from tablename;

                It is used for displaying the contents of the table

.

           4.TRUNCATE COMMAND:

                 Syntax:

                               Truncate table tablename;

                The contents of the table are deleted(truncate).

            5.DROP COMMAND:

                   Syntax:

                               Drop table tablename;

                    The whole table ifself is delected.

OUTPUT:

SQL> create table robo(name varchar(10),brand number(5));

Table created.

SQL> desc robo

 Name                            Null?    Type

 ------------------------------- -------- ----

 NAME                                     VARCHAR2(10)

 BRAND                                    NUMBER(5)

SQL> insert into robo values('&name','&brand');

Enter value for name: priya

Enter value for brand: 100

old   1: insert into robo values('&name','&brand')

new   1: insert into robo values('priya','100')

1 row created.

SQL> insert into robo values('&name','&brand');

Enter value for name: riya

Enter value for brand: 1001

old   1: insert into robo values('&name','&brand')

new   1: insert into robo values('riya','1001')

1 row created.

SQL> insert into robo values('&name','&brand');

Enter value for name: supriya

Enter value for brand: 10011

old   1: insert into robo values('&name','&brand')

new   1: insert into robo values('supriya','10011')

1 row created.

SQL> select * from robo;

NAME           BRAND

---------- ---------

priya            100

riya            1001

supriya        10011

SQL> alter table robo add(price number(5));

Table altered.

SQL> desc robo

 Name                            Null?    Type

 ------------------------------- -------- ----

 NAME                                     VARCHAR2(10)

 BRAND                                    NUMBER(5)

 PRICE                                    NUMBER(5)

SQL> alter table robo modify(price number(5));

Table altered.

SQL> desc robo

 Name                            Null?    Type

 ------------------------------- -------- ----

 NAME                                     VARCHAR2(10)

 BRAND                                    NUMBER(5)

 PRICE                                    NUMBER(5)

SQL> truncate table robo;

Table truncated.

SQL> desc robo

 Name                            Null?    Type

 ------------------------------- -------- ----

 NAME                                     VARCHAR2(10)

 BRAND                                    NUMBER(5)

 PRICE                                    NUMBER(5)

SQL> select * from robo;

no rows selected

SQL> drop table robo;

Table dropped.

Posted in: MySQL