Record

April 6, 2021

Records in DBMS

Generally, the database table is viewed as a collection of records
The term record is often also called tuple and row in a database table

RECORD

Each record represents complete information of the specific data item, each record stores different data with the same structure

Example : For example in an employee table, we need to store the details of 10 employees then the database table will consist of 10 records every each record contains details of that particular employee i.e 1 record for storing the information of one employee

Consider a sample table ‘emp’

ENAME	JOB	SAL	HIREDATE	HIREDATE+2
KING	PRESIDENT	5000	17-NOV-81	19-NOV-81
BLAKE	MANAGER	2850	01-MAY-81	03-MAY-81
CLARK	MANAGER	2450	09-JUN-81	11-JUN-81
JONES	MANAGER	2975	02-APR-81	04-APR-81
SCOTT	ANALYST	3000	19-APR-87	21-APR-87
FORD	ANALYST	3000	03-DEC-81	05-DEC-81
SMITH	CLERK	800	17-DEC-80	19-DEC-80

Table contents seven rows i.e it stores the details of all the 7 employees in 7 separate records

SQL Query to retrieve particular records

SELECT * FROM EMP
WHERE DEPTNO=20;

Output :
4 rows selected.

EMPNO	ENAME	JOB	MGR	HIREDATE	SAL	COMM	DEPTNO
7566	JONES	MANAGER	7839	02-APR-81	2975	–	20
7788	SCOTT	ANALYST	7566	19-APR-87	3000	–	20
7902	FORD	ANALYST	7566	03-DEC-81	3000	–	20
7369	SMITH	CLERK	7902	17-DEC-80	800	500	20

Only those rows corresponding to the details of Department number 20 are displayed

ROW NUM in SQL

The rownum clause in SQL is used to specify the number of rcords present in a database table
Each record will be added a number starting from 1 to n so that the user can easily identify the number of records present in the table

Example

select rownum,empno,ename,job,sal,deptno 
FROM EMP;

Output :
7 rows selected.

ROWNUM	EMPNO	ENAME	JOB	SAL	DEPTNO
1	7839	KING	PRESIDENT	5000	10
2	7698	BLAKE	MANAGER	2850	30
3	7782	CLARK	MANAGER	2450	10
4	7566	JONES	MANAGER	2975	20
5	7788	SCOTT	ANALYST	3000	20
6	7902	FORD	ANALYST	3000	20
7	7369	SMITH	CLERK	800	20

Displaying top N records

Suppose if you want to display the top three records present in emp table then you can use this rownum along with the relational operator