出力される行数を求める（COUNT関数）

COUNT関数を使用することで、選択されたレコードの数を出力できます。

mysql&gt; select COUNT(*) from member;
+----------+
| COUNT(*) |
+----------+
|       14 |
+----------+
1 row in set (0.00 sec)

mysql&gt; select COUNT(*) from member where address="東京";
+----------+
| COUNT(*) |
+----------+
|        2 |
+----------+
1 row in set (0.00 sec)

mysql> select COUNT(*) from member;

+----------+

| COUNT(*) |

+----------+

| 14 |

+----------+

1 row in set (0.00 sec)

mysql> select COUNT(*) from member where address="東京";

+----------+

| COUNT(*) |

+----------+

| 2 |

+----------+

1 row in set (0.00 sec)