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प्रश्न
What is a constraint?
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उत्तर
Constraint:
- The constraint is a condition applicable on a field or set of fields.
- Constraints are used to limit the type of data that can go into a table.
- This ensures the accuracy and reliability of the data in the database.
- Constraints could be either on a column level or a table level.
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संबंधित प्रश्न
The command to delete a table is ______
The clause used to sort data in a database.
Write the difference between table constraint and column constraint?
Write a SQL statement to modify the student table structure by adding a new field.
Consider the following employee table. Write SQL commands for the question.
| EMP CODE | NAME | DESIG | PAY | ALLO WANCE |
| S1001 | Hariharan | Supervisor | 29000 | 12000 |
| P1002 | Shaji | Operator | 10000 | 5500 |
| P1003 | Prasad | Operator | 12000 | 6500 |
| C1004 | Manjima | Clerk | 8000 | 4500 |
| M1005 | Ratheesh | Mechanic | 20000 | 7000 |
To remove the employees who are mechanics.
Consider the following employee table. Write SQL commands for the question.
| EMP CODE | NAME | DESIG | PAY | ALLO WANCE |
| S1001 | Hariharan | Supervisor | 29000 | 12000 |
| P1002 | Shaji | Operator | 10000 | 5500 |
| P1003 | Prasad | Operator | 12000 | 6500 |
| C1004 | Manjima | Clerk | 8000 | 4500 |
| M1005 | Ratheesh | Mechanic | 20000 | 7000 |
To add a new row.
Consider the following employee table. Write SQL commands for the question.
| EMP CODE | NAME | DESIG | PAY | ALLO WANCE |
| S1001 | Hariharan | Supervisor | 29000 | 12000 |
| P1002 | Shaji | Operator | 10000 | 5500 |
| P1003 | Prasad | Operator | 12000 | 6500 |
| C1004 | Manjima | Clerk | 8000 | 4500 |
| M1005 | Ratheesh | Mechanic | 20000 | 7000 |
To display the details of all employees who are operators.
Construct the following SQL statement in the student table-
SELECT statement using GROUP BY clause.
Construct the following SQL statement in the student table-
SELECT statement using ORDER BY clause.
Write a SQL statement to create a table for employees having any five fields and create a table constraint for the employee table.
