Tuple
Tuples in DBMS
On this page, we will learn about Tuple in DBMS.
- Generally, the database table is viewed as a collection of tuples.
- The term
tupleis often also calledrowandrecordin a database table.
TUPLE
Each tuple represents a complete record of the specific data item, each tuple 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 tuples every each tuple contains details of that particular employee i.e 1 tuple for storing the record 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 tuples
SQL Query to retrieve particular tuples
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 tuples 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 tuples present in a database table
- Each tuple will be added a number starting from 1 to n so that the user can easily identify the number of tuple 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 tuples
Suppose if you want to display the top three tuples 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 tuples in a table or displayed
Prime Course Trailer
Related Banners
Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription
Get over 200+ course One Subscription
Courses like AI/ML, Cloud Computing, Ethical Hacking, C, C++, Java, Python, DSA (All Languages), Competitive Coding (All Languages), TCS, Infosys, Wipro, Amazon, DBMS, SQL and others
Login/Signup to comment