DATA DICTIONARY LANGUAGE (DDL) ( CREATE, ALTER, DROP, TRUNCATE, RENAME)

DATA DICTIONARY LANGUAGE (DDL) ( CREATE, ALTER, DROP, TRUNCATE, RENAME)

Creating a table

create table Employee
(empno number(2),
ename varchar2(30),
sal number(10,2) ) ;
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- create a
create table student
(rollno number(4),
sname varchar2(20),
DOB date,
Branch varchar2(20));

Altering a table by using Add, Modify, Drop, Rename

alter table student add address varchar(100) ;
alter table stdeunt add (address1 varchar(100), fname varchar2(30)) ;
alter table student modify (address varchar2(50), address1 varchar2(50)) ;

- Dropping a column in student table
alter table student drop column address1 ;

- To drop multiple columns at a time is:
Alter table student drop (FNAME, branch) ;

- To renaming a column
Alter table emp rename column ename to empname ;

- To seeting the Unused columns SAL in EMP table
Alter table emp set UNUSED COLUMN Sal;

- Dropping the unused columnfrom the EMPtable
Alter table emp DROP UNUSED COLUMNS;

Dropping a table

Drop table tablename ;

DROP table tname ;
Drop table emp1 ;

Truncating a Table
truncate table dept;

Renaming a table
Rename oldtablename to newtabalename;
Rename emp to emp1 ;