1 row in set (0.00 sec)
81 T_B_USER 26
72 T_B_NOTICE 15

复制代码 代码如下:

mysql> select count(*) from columns where table_name="test";
Database changed

mysql> desc test;

下面是通过大致查看：
直接利用函数来解决：

| 3 |

复制代码 代码如下:

+---------+-------------+------+-----+---------+----------------+
select count(column_name) from user_tab_columns where table_name='T_B_AUDITOR'
75 T_B_ORGANIZATIONINFO 18
| table_schema | count(*) |
84 T_B_USERMODEL 6
69 T_B_FILTERWORD 11
67 T_B_BOOKSTATUSCONFIG 5
80 T_B_SAMPLEBOOKINFO 89
在mysql中想要知道数据库中有多少个库：
能够查出来指定的那张表的字段数。

此时我就联想到了mysql上面去：
3 rows in set (0.00 sec)
| NULL | mysql | utf8 | utf8_general_ci | NULL |
76 T_B_PREFIXINFO 15
| mysql | 17 |
其实在系统表information_schema中大多的数据库，表啊都会有记录的。所以要好好研究下这张表呢。
还有就是利用系统表：
| information_schema | 17 |

复制代码 代码如下:

+---------+-------------+------+-----+---------+----------------+
78 T_B_ROLE 8

+----------+
mysql> select table_schema,count(*) from tables group by table_schema;
mysql> select * from schemata;
| name | varchar(10) | YES | | NULL | |

复制代码 代码如下:

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

| test | 6 |
| NULL | test | utf8 | utf8_general_ci | NULL |
+----------+

mysql> use information_schema
73 T_B_NOTICEACCEPT 11

复制代码 代码如下:

74 T_B_OPERLOG 10
3 rows in set (0.01 sec)
| NULL | information_schema | utf8 | utf8_general_ci | NULL |
83 T_B_USERLOGIN 8
+--------------------+----------+
| address | varchar(30) | YES | | NULL | |

68 T_B_CODETREEINFO 8
71 T_B_MODEL 10
Oracle中查询某个表的总字段数，要用SQL语句，或者在PL/SQL里面
+--------------+--------------------+----------------------------+------------------------+----------+
+--------------+
在mysql数据库中有多少张表：
| 3 |

| Field | Type | Null | Key | Default | Extra |

+--------------------+----------+
+--------------+
1 row in set (0.01 sec)
65 T_B_AUDITOR 14
79 T_B_ROLEMODEL 6
3 rows in set (0.00 sec)
+--------------------+----------+
select tname,count(*) from col group by tname;
| CATALOG_NAME | SCHEMA_NAME | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME | SQL_PATH |
| count(*) |

+--------------+
70 T_B_ISBNWHITELIST 11
+--------------+--------------------+----------------------------+------------------------+----------+

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

| found_rows() |
+---------+-------------+------+-----+---------+----------------+

64 T_A_BOOKSTAGEINFO 4
mysql> select found_rows();
82 T_B_USERANDROLE 6

复制代码 代码如下:

| id | int(11) | NO | PRI | NULL | auto_increment |
66 T_B_BOOKMANAGEMENT 13
77 T_B_PUBLISHINFO 30