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प्रश्न
Differentiate between count() and count(*) functions in SQL with appropriate examples.
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उत्तर
COUNT(*) returns the count of all rows in the table, whereas COUNT() is used with Column_Name passed as an argument and counts the number of non-NULL values in a column that is given as an argument.
Example: Table: EMPL
| EMPNO | ENAME | JOB | SAL | DEPTNO |
| 8270 | JACK | SALESMAN | 2985 | 10 |
| 8566 | ALI | CLERK | 9870 | 20 |
| 8922 | AJAY | NULL | 8760 | 30 |
| 8736 | BINDU | CLERK | 5643 | 20 |
| 8822 | JOY | MANAGER | 3000 | 10 |
e.g. SELECT COUNT(*) FROM EMPL;
Output
| COUNT(*) |
| 5 |
e.g. SELECT COUNT(JOB) FROM EMPL;
Output
| COUNT(JOB) |
| 4 |
Since JOB has 1 NULL value.
APPEARS IN
संबंधित प्रश्न
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| 1 | Anand | XI | 6/6/97 | M | Agra | 430 |
| 2 | Chetan | XII | 7/5/94 | M | Mumbai | 460 |
| 3 | Geet | XI | 6/5/97 | F | Agra | 470 |
| 4 | Preeti | XII | 8/8/95 | F | Mumbai | 492 |
| 5 | Saniyal | XII | 8/10/95 | M | Delhi | 360 |
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| Anand |
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