CHECK TABLE ENTRY:

SQL> select table_name from user_tables;

Employee Salary statistics
TABLE_NAME
------------------------------
BONUS
DEPT
EMP
SALGRADE
SQL>

CREATE TABLE:

SQL> select table_name from user_tables;

Employee Salary statistics
TABLE_NAME
------------------------------
BONUS
DEPT
EMP
SALGRADE
SQL>
SQL>
SQL> create table students
2 (
3 StidentID number(6),
4 Firstname varchar2(30),
5 LastNmae varchar2(30),
6 Address varchar2(50)
7 );

Table created.

SQL> select table_name from user_tables;

Employee Salary statistics
TABLE_NAME
------------------------------
BONUS
DEPT
EMP
SALGRADE
STUDENTS
SQL> describe students
Name Null? Type
----------------------------------------- -------- ----------------
STIDENTID NUMBER(6)
FIRSTNAME VARCHAR2(30)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL>

EXAMPLE 2:

SQL>
SQL> create table enrolment (EnrolmentID number(6), StudentID number(6), SessionID number(6));
SQL> desc enrolment
Name Null? Type
----------------------------------------- -------- ----------------------------
ENROLMENTID NUMBER(6)
STUDENTID NUMBER(6)
SESSIONID NUMBER(6)

SQL>

EXAMPLE 3:

SQL> create table sessions (SessionID number(6), StartID date, EndID date, CourseID number(6), Inst
ructorID number(6), LocationID number(6));
SQL> desc sessions
Name Null? Type
----------------------------------------- -------- ----------------------------
SESSIONID NUMBER(6)
STARTID DATE
ENDID DATE
COURSEID NUMBER(6)
INSTRUCTORID NUMBER(6)
LOCATIONID NUMBER(6)

SQL>

EXAMPLE 4:

copy and create new table from existing table

SQL> create table instructors as select * from students;

TO DELETE TABLE (using drop table):

TO CHECK THE EXISTING OF TABLE IN THE DATABASE.

SQL> select table_name from user_tables;

Employee Salary statistics
TABLE_NAME
------------------------------
BONUS
DEPT
EMP
SALGRADE
STUDENTS
SQL>

Then you can delete table by using drop command:

example:

SQL>
SQL> DROP TABLE STUDENTS;
SQL> DESC STUDENTS
ERROR:
ORA-04043: object STUDENTS does not exist


SQL> select table_name from user_tables;

Employee Salary statistics
TABLE_NAME
------------------------------
BONUS
DEPT
EMP
SALGRADE
SQL>

Rename table:

SQL> rename enrolllement to enrollments;

Table renamed.

DELETTTTTTTTTT

SQL>
SQL> desc instructors
Name Null? Type
----------------------------------------- -------- -------------------
STIDENTID NUMBER(6)
FIRSTNAME VARCHAR2(30)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL> alter table instructors SET UNUSED COLUMN stidentid;

Table altered.

SQL> desc instructors
Name Null? Type
----------------------------------------- -------- ---------------
FIRSTNAME VARCHAR2(30)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL>

ALTER SPACEeeeee

SQL> desc instructors
Name Null? Type
----------------------------------------- -------- ----------------------
FIRSTNAME VARCHAR2(30)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL> alter table instructors MODIFY (firstname VARCHAR2(6));

Table altered.

SQL> desc instructors
Name Null? Type
----------------------------------------- -------- ----------------------
FIRSTNAME VARCHAR2(6)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL>

NOT NULL to make sure that user have to enter value:

SQL> desc instructors
Name Null? Type
----------------------------------------- -------- ----------------------
FIRSTNAME VARCHAR2(6)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL> alter table instructors MODIFY (firstname NOT NULL);

Table altered.

SQL> desc instructors
Name Null? Type
----------------------------------------- -------- ----------------------
FIRSTNAME NOT NULL VARCHAR2(6)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL>

EXAMPLE 2:

SQL> desc instructors
Name Null? Type
----------------------------------------- -------- --------------------
FIRSTNAME NOT NULL VARCHAR2(6)
LASTNMAE VARCHAR2(30)
ADDRESS VARCHAR2(50)

SQL> alter table instructors
2 modify
3 (
4 lastnmae NOT NULL,
5 address NOT NULL
6 );

Table altered.

SQL> desc instructors
Name Null? Type
----------------------------------------- -------- --------------------
FIRSTNAME NOT NULL VARCHAR2(6)
LASTNMAE NOT NULL VARCHAR2(30)
ADDRESS NOT NULL VARCHAR2(50)

SQL>

To MAKE SURE unix ness of user id:

xxxxxxxxxxxxx tak sempat

INSERT DATA in table

SQL>insert into [table] (row1,row2,row3) value (1,'ggg','hhh');