ROW in DBMS

ROW

Each row represents a complete record of the specific data item, each row 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 rows every each row contains details of that particular employee i.e 1 row for storing the record of one employee Consider a sample table ‘emp’ Table contents seven rows i.e it stores the details of all the 7 employees in 7 separate rows.

SQL Query to retrieve particular rows

SELECT * FROM EMP
WHERE DEPTNO=20;

O/P

4 rows selected.

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 rows present in a database table
• Each row will be added a number starting from 1 to n so that the user can easily identify the number of rows present in the table

Example

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

O/P

7 rows selected.

Displaying top N rows

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

Example

select rownum,empno,ename,job,sal,deptno 
FROM EMP
where rownum<=3;

O/P

3 rows selected.

Only the first 3 rows in a table or displayed