COUNT() and GROUP BY : Count « Select Clause « SQL / MySQL






  1. SQL / MySQL
  2. Select Clause
  3. Count

COUNT() and GROUP BY

/*

mysql> /*  COUNT() and GROUP BY
mysql> Number of animals per species:
mysql> */
mysql> SELECT species, COUNT(*) FROM Bird GROUP BY species;
+---------+----------+
| species | COUNT(*) |
+---------+----------+
| Bus     |        2 |
| Car     |        1 |
+---------+----------+
2 rows in set (0.00 sec)


*/  
Drop table Bird;

CREATE TABLE Bird (
    name VARCHAR(20), 
    owner VARCHAR(20),
    species VARCHAR(20), 
    sex CHAR(1), 
    birth DATE, 
    death DATE
);
  
INSERT INTO  Bird VALUES ('BlueBird','Joe','Car','f','1999-03-30',NULL);
INSERT INTO  Bird VALUES ('RedBird','Yin','Bus','m','1979-04-30',1998-01-30);
INSERT INTO  Bird VALUES ('RedBird','Yin','Bus','m','1998-01-30',NULL);


/*  COUNT() and GROUP BY 

Number of animals per species:
*/
SELECT species, COUNT(*) FROM Bird GROUP BY species;








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1.Counting Rows: Counting the total number of animals
2.Count and group
3.Use COUNT in select command
4.Another Count and Group BY
5.Count and group by two columns
6.COUNT command with condition
7.COUNT with condition and group
8.Get GROUP BY for COUNT
9.Use COUNT with condition
10.Simple COUNT
11.Performing Row and Column Counting
12.Use COUNT and GROUP
13.Use COUNT, GROUP and HAVING