RECORD
Record 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. On this page, we will learn about Record in DBMS.
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 records 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.
Example
select rownum,empno,ename,job,sal,deptno FROM EMP where rownum<=3;
Output: 3 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 |
Only the first 3 records in a table or displayed
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