how many different drivers there are, use COUNT(DISTINCT)

       
mysql>
mysql> CREATE TABLE mytable
    -> (
    ->  rec_id          INT UNSIGNED NOT NULL AUTO_INCREMENT,
    ->  name            VARCHAR(20) NOT NULL,
    ->  trav_date       DATE NOT NULL,
    ->  miles           INT NOT NULL,
    ->  PRIMARY KEY (rec_id)
    -> );
Query OK, 0 rows affected (0.01 sec)

mysql>
mysql> INSERT INTO mytable (name,trav_date,miles)
    ->  VALUES
    ->          ('Ben','2010-11-30',152),
    ->          ('Suzi','2010-11-29',391),
    ->          ('Henry','2010-11-29',300),
    ->          ('Henry','2010-11-27',96),
    ->          ('Ben','2010-11-29',131),
    ->          ('Henry','2010-11-26',115),
    ->          ('Suzi','2010-12-02',502),
    ->          ('Henry','2010-12-01',197),
    ->          ('Ben','2010-12-02',79),
    ->          ('Henry','2010-11-30',203)
    -> ;
Query OK, 10 rows affected (0.00 sec)
Records: 10  Duplicates: 0  Warnings: 0

mysql>
mysql> SELECT COUNT(DISTINCT name) FROM mytable;
+----------------------+
| COUNT(DISTINCT name) |
+----------------------+
|                    3 |
+----------------------+
1 row in set (0.00 sec)

mysql>
mysql> drop table mytable;
Query OK, 0 rows affected (0.00 sec)

Related examples in the same category

1.	Use DISTINCT to get non-dupliate records
2.	Use DISTICNT to get unique value
3.	Eliminating Duplicate Data Using DISTINCT 1
4.	Eliminating Duplicate Data Using DISTINCT 2
5.	Select distinct records using JOIN
6.	The SQL key word DISTINCT has the effect that equivalent data records are output only once.
7.	DISTINCT works with multiple-column output too.
8.	DISTINCT with two columns
9.	DISTINCT works with expressions, not just column values.
10.	Inserting name values into the multisequence table generates separate sequences for each distinct name:
11.	Count distinct
12.	Distinct sub string
13.	Average distinct value
14.	Return a list of surnames, with each surname appearing only once?
15.	The fraction of the records that contain unique or non-unique names:

how many different drivers there are, use COUNT(DISTINCT) : Distinct « Select Clause « SQL / MySQL

Related examples in the same category