Spec-Zone .ru
спецификации, руководства, описания, API
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If you do not want to see entire rows from your table, just name the columns in which you are interested,
separated by commas. For example, if you want to know when your animals were born, select the name
and birth
columns:
mysql> SELECT name, birth FROM pet;
+----------+------------+| name | birth |+----------+------------+| Fluffy | 1993-02-04 || Claws | 1994-03-17 || Buffy | 1989-05-13 || Fang | 1990-08-27 || Bowser | 1989-08-31 || Chirpy | 1998-09-11 || Whistler | 1997-12-09 || Slim | 1996-04-29 || Puffball | 1999-03-30 |+----------+------------+
To find out who owns pets, use this query:
mysql> SELECT owner FROM pet;
+--------+| owner |+--------+| Harold || Gwen || Harold || Benny || Diane || Gwen || Gwen || Benny || Diane |+--------+
Notice that the query simply retrieves the owner
column from each record, and some
of them appear more than once. To minimize the output, retrieve each unique output record just once by adding
the keyword DISTINCT
:
mysql> SELECT DISTINCT owner FROM
pet;
+--------+| owner |+--------+| Benny || Diane || Gwen || Harold |+--------+
You can use a WHERE
clause to combine row selection with column selection. For
example, to get birth dates for dogs and cats only, use this query:
mysql>SELECT name, species, birth FROM pet
->WHERE species = 'dog' OR species = 'cat';
+--------+---------+------------+| name | species | birth |+--------+---------+------------+| Fluffy | cat | 1993-02-04 || Claws | cat | 1994-03-17 || Buffy | dog | 1989-05-13 || Fang | dog | 1990-08-27 || Bowser | dog | 1989-08-31 |+--------+---------+------------+