解析如何查看Oracle数据库中某张表的字段个数
解析如何查看Oracle数据库中某张表的字段个数
发布时间:2016-12-28 来源:查字典编辑
摘要:Oracle中查询某个表的总字段数,要用SQL语句,或者在PL/SQL里面复制代码代码如下:selectcount(column_name)...

Oracle中查询某个表的总字段数,要用SQL语句,或者在PL/SQL里面

复制代码 代码如下:

select count(column_name) from user_tab_columns where table_name='T_B_AUDITOR'

能够查出来指定的那张表的字段数。

下面是通过大致查看:

select tname,count(*) from col group by tname;

复制代码 代码如下:

64T_A_BOOKSTAGEINFO4

65T_B_AUDITOR14

66T_B_BOOKMANAGEMENT13

67T_B_BOOKSTATUSCONFIG5

68T_B_CODETREEINFO8

69T_B_FILTERWORD11

70T_B_ISBNWHITELIST11

71T_B_MODEL10

72T_B_NOTICE15

73T_B_NOTICEACCEPT11

74T_B_OPERLOG10

75T_B_ORGANIZATIONINFO18

76T_B_PREFIXINFO15

77T_B_PUBLISHINFO30

78T_B_ROLE8

79T_B_ROLEMODEL6

80T_B_SAMPLEBOOKINFO89

81T_B_USER26

82T_B_USERANDROLE6

83T_B_USERLOGIN8

84T_B_USERMODEL6

此时我就联想到了mysql上面去:

直接利用函数来解决:

复制代码 代码如下:

mysql> desc test;

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

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

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

| id | int(11) | NO | PRI | NULL | auto_increment |

| name | varchar(10) | YES | | NULL | |

| address | varchar(30) | YES | | NULL | |

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

3 rows in set (0.01 sec)

mysql> select found_rows();

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

| found_rows() |

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

| 3 |

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

1 row in set (0.01 sec)

还有就是利用系统表:

复制代码 代码如下:

mysql> use information_schema

Database changed

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

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

| count(*) |

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

| 3 |

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

1 row in set (0.00 sec)

在mysql中想要知道数据库中有多少个库:

复制代码 代码如下:

mysql> select * from schemata;

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

| CATALOG_NAME | SCHEMA_NAME | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME | SQL_PATH |

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

| NULL | information_schema | utf8 | utf8_general_ci | NULL |

| NULL | mysql | utf8 | utf8_general_ci | NULL |

| NULL | test | utf8 | utf8_general_ci | NULL |

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

3 rows in set (0.00 sec)

在mysql数据库中有多少张表:

复制代码 代码如下:

mysql> select table_schema,count(*) from tables group by table_schema;

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

| table_schema | count(*) |

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

| information_schema | 17 |

| mysql | 17 |

| test | 6 |

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

3 rows in set (0.00 sec)

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。

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