SQL COUNT function is the simplest function and very useful in counting the number of records, which are expected to be returned by a SELECT statement.
To understand the COUNT function, consider an employee_tbl table, which is having the following records −
SQL> SELECT * FROM employee_tbl;
+------+------+------------+--------------------+
| id | name | work_date | daily_typing_pages |
+------+------+------------+--------------------+
| 1 | John | 2007-01-24 | 250 |
| 2 | Ram | 2007-05-27 | 220 |
| 3 | Jack | 2007-05-06 | 170 |
| 3 | Jack | 2007-04-06 | 100 |
| 4 | Jill | 2007-04-06 | 220 |
| 5 | Zara | 2007-06-06 | 300 |
| 5 | Zara | 2007-02-06 | 350 |
+------+------+------------+--------------------+
7 rows in set (0.00 sec)
Now suppose based on the above table you want to count the total number of rows in this table, then you can do it as follows −
SQL>SELECT COUNT(*) FROM employee_tbl ;
+----------+
| COUNT(*) |
+----------+
| 7 |
+----------+
1 row in set (0.01 sec)
Similarly, if you want to count the number of records for Zara, then it can be done as follows −
SQL>SELECT COUNT(*) FROM employee_tbl
-> WHERE name="Zara";
+----------+
| COUNT(*) |
+----------+
| 2 |
+----------+
1 row in set (0.04 sec)
NOTE − All the SQL queries are case insensitive, so it does not make any difference if you give ZARA or Zara in WHERE CONDITION.
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