获取表字段数目

Question

如何在动态获取表字段的同时，动态获取表字段数目？请告诉帮忙

Answer 1

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| csdn               |
| discuz             |
| ecshop             |
| images             |
| mysql              |
| phpmyadmin         |
| sourcedata         |
| teachdata          |
| test               |
+--------------------+
10 rows in set (0.00 sec)mysql> use information_schema;
Database changed
mysql> show tables;
+---------------------------------------+
| Tables_in_information_schema          |
+---------------------------------------+
| CHARACTER_SETS                        |
| COLLATIONS                            |
| COLLATION_CHARACTER_SET_APPLICABILITY |
| COLUMNS                               |
| COLUMN_PRIVILEGES                     |
| KEY_COLUMN_USAGE                      |
| PROFILING                             |
| ROUTINES                              |
| SCHEMATA                              |
| SCHEMA_PRIVILEGES                     |
| STATISTICS                            |
| TABLES                                |
| TABLE_CONSTRAINTS                     |
| TABLE_PRIVILEGES                      |
| TRIGGERS                              |
| USER_PRIVILEGES                       |
| VIEWS                                 |
+---------------------------------------+
17 rows in set (0.00 sec)mysql> select t1.column_name,t2.cc from columns t1,
    -> (select count(*) cc from columns where table_schema='csdn'
    -> and table_name='orders') t2
    -> where t1.table_schema='csdn'
    -> and t1.table_name='orders';
+-------------+----+
| column_name | cc |
+-------------+----+
| id          |  4 |
| bno         |  4 |
| type        |  4 |
| dd          |  4 |
+-------------+----+
4 rows in set (0.01 sec)mysql> desc csdn.orders;
+-------+----------+------+-----+---------+-------+
| Field | Type     | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id    | int(11)  | YES  |     | NULL    |       |
| bno   | int(11)  | YES  |     | NULL    |       |
| type  | int(11)  | YES  |     | NULL    |       |
| dd    | datetime | YES  |     | NULL    |       |
+-------+----------+------+-----+---------+-------+
4 rows in set (0.00 sec)

Answer 2

mysql> select group_concat(t1.column_name) as fields,t2.cc
    -> from columns t1,
    -> (select count(*) cc from columns
    -> where table_schema='csdn'
    -> and table_name='orders')t2
    -> where t1.table_schema='csdn'
    -> and t1.table_name='orders'
    -> group by t1.table_name;
+----------------+----+
| fields         | cc |
+----------------+----+
| id,bno,type,dd |  4 |
+----------------+----+
1 row in set (0.00 sec)