TABLE CREATION:

CREATE TABLE employeerecord(employee_no number(5),employee_name varchar(15),department_no number(5),salary_no number(5),dateofjoin date,job varchar(20));

Table created.SQL> desc employeerecordName Null? Type----------------------------------------- -------- ----------------EMPLOYEE_NO NUMBER(5)EMPLOYEE_NAME VARCHAR2(15)DEPARTMENT VARCHAR2(5)SALARY_NO NUMBER(5)DATEOFJOIN DATEJOB VARCHAR2(20)

ALTER THE TABLE:

ADD:SQL> ALTER TABLE employeerecord ADD dateofbirth date;

Table altered.

SQL> desc employeerecord

Name Null? Type----------------------------------------- -------- ----------------EMPLOYEE_NO NUMBER(5)EMPLOYEE_NAME VARCHAR2(15)DEPARTMENT VARCHAR2(5)SALARY_NO NUMBER(5)DATEOFJOIN DATEJOB VARCHAR2(20)DATEOFBIRTH DATE

DROP THE COLUMN:

SQL> ALTER TABLE employeerecord DROP COLUMN place;

Table altered.SQL> desc employeerecordName Null? Type----------------------------------------- -------- ----------------EMPLOYEE_NO NUMBER(5)EMPLOYEE_NAME VARCHAR2(30)DEPARTMENT VARCHAR2(5)SALARY_NO NUMBER(5)DATEOFJOIN DATEJOB VARCHAR2(50)

MODIFY:

SQL> ALTER TABLE employeerecord modify employee_no int;

Table altered.

SQL> desc employeerecordName Null? Type----------------------------------------- -------- -----------------EMPLOYEE_NO NUMBER(38)EMPLOYEE_NAME VARCHAR2(30)DEPARTMENT VARCHAR2(5)SALARY_NO NUMBER(5)DATEOFJOIN DATEDATEOFBIRTH DATEJOB VARCHAR2(50)

TRUNCATE:

SQL> TRUNCATE TABLE employeerecord ;

Table truncated.

INTEGRITY CONSTRAINTS:

SQL>CREATE TABLE employee_record(employee_no number(5),employee_name varchar(15),department_no int NOT NULL PRIMARY KEY,job varchar(20));

Table created.

SQL> desc employee_record;Name Null? Type----------------------------------------- -------- ----------------------------EMPLOYEE_NO NUMBER(5)EMPLOYEE_NAME VARCHAR2(15)DEPARTMENT_NO NOT NULL NUMBER(38)JOB VARCHAR2(20)

SQL>CREATE TABLE department (department_no int NOT NULL PRIMARY KEY,department_name varchar(20),employee_no int NOT NULL,FOREIGN KEY (department_no) REFERENCES employee_record022(department_no) );

SQL> desc departmentName Null? Type----------------------------------------- -------- --------------DEPARTMENT_NO NOT NULL NUMBER(38)DEPARTMENT_NAME VARCHAR2(20)EMPLOYEE_NO NOT NULL NUMBER(38)

SQL>ALTER TABLEemployeerecordADD UNIQUE(employee_no);

Table altered.

SQL>ALTER TABLEemployeerecordDROP UNIQUE(employee_no);

Table altered.

SQL> ALTER TABLE employeerecord ADD CONSTRAINT uc_employee UNIQUE (employee_no,e_name);

Table altered.

SQL> ALTER TABLE employeerecord DROP CONSTRAINT uc_employee;

Table altered.

SQL> desc employeerecord; Name Null? Type----------------------------------------- -------- -----------------EMPLOYEE_NO NUMBER(38)EMPLOYEE_NAME VARCHAR2(30)DEPARTMENT NOTNULL VARCHAR2(5)JOB VARCHAR2(50)SQL>ALTERTABLEemployeerecord ADD CONSTRAINTpk_employee PRIMARY KEY (employee_no);

SQL> desc employeerecordName Null? Type----------------------------------------- -------- -----------------EMPLOYEE_NO NOTNULL NUMBER(38)EMPLOYEE_NAME VARCHAR2(30)DEPARTMENT NOTNULL VARCHAR2(5)JOB VARCHAR2(50)

SQL>ALTER TABLEemployeerecordDROP CONSTRAINTpk_employee;

Table altered.

SQL> desc employeerecord; Name Null? Type----------------------------------------- -------- -----------------EMPLOYEE_NO NUMBER(38)EMPLOYEE_NAME VARCHAR2(30)DEPARTMENT NOTNULL VARCHAR2(5)JOB VARCHAR2(50)

SQL>ALTER TABLEemployeerecordADD CONSTRAINTchk_employee CHECK (employee_no>0);

Table altered.

SQL>ALTER TABLEemployeerecord DROP CONSTRAINTchk_employee;

Table altered.

SQL>DROP TABLEemployeerecord;

Table dropped.

SQL> desc employeerecordERROR:ORA-04043: object employeerecord does not exist