Oracle查询数据表结构(字段,类型,大小,备注)

创建表的SQL语句如下 -- 创建数据表 create table TABLE_TEST ( NAME varchar2(40) not null, SEX varchar2(1) default ''''Y'''' not null, BIRTHDAY date not null, HEIGHT number(3,2), WEIGHT number(3,2), MEMO blob ); -- 给列添加备注 comment on col

创建表的SQL语句如下
-- 创建数据表
create table TABLE_TEST
(
    NAME varchar2(40) not null,
    SEX varchar2(1) default ''''Y'''' not null,
    BIRTHDAY date not null,
    HEIGHT number(3,2),
    WEIGHT number(3,2),
    MEMO blob
);
-- 给列添加备注
  comment on column TABLE_TEST.NAME is ''''姓名'''';
  comment on column TABLE_TEST.SEX is ''''性别'''';
  comment on column TABLE_TEST.BIRTHDAY is ''''生日'''';
  comment on column TABLE_TEST.HEIGHT is ''''身高'''';
  comment on column TABLE_TEST.WEIGHT is ''''体重'''';
  comment on column TABLE_TEST.MEMO is ''''备注'''';
-- 创建约束关系 主键 外键 其他
  alter table TABLE_TEST add constraint TB_TEST_P_NAME primary key (NAME);

数据表创建完毕，执行下列SQL语句：
select
    A.column_name 字段名,A.data_type 数据类型,A.data_length 长度,A.data_precision 整数位,
    A.Data_Scale 小数位,A.nullable 允许空值,A.Data_default 缺省值,B.comments 备注
from
    user_tab_columns A,user_col_comments B
where
    A.Table_Name = B.Table_Name
    and A.Column_Name = B.Column_Name
    and A.Table_Name = ''''TABLE_TEST''''

我们可以得出一下结果：

<strong><span><span>字段名</span></span></strong>	<strong><span><span>数据类型</span></span></strong>	<strong><span><span>长度</span></span></strong>	<strong><span><span>整数位</span></span></strong>	<strong><span><span>小数位</span></span></strong>	<strong><span><span>允许空值</span></span></strong>	<strong><span><span>缺省值</span></span></strong>	<strong><span><span>备注</span></span></strong>
<span><span>NAME</span></span>	<span><span>VARCHAR2</span></span>	<span><span>40</span></span>	<span></span>	<span></span>	<span><span>N</span></span>	<span><span><long></long></span></span>	<span><span>姓名</span></span>
<span><span>SEX</span></span>	<span><span>VARCHAR2</span></span>	<span><span>1</span></span>	<span></span>	<span></span>	<span><span>N</span></span>	<span><span><long></long></span></span>	<span><span>性别</span></span>
<span><span>BIRTHDAY</span></span>	<span><span>DATE</span></span>	<span><span>7</span></span>	<span></span>	<span></span>	<span><span>N</span></span>	<span><span><long></long></span></span>	<span><span>生日</span></span>
<span><span>HEIGHT</span></span>	<span><span>NUMBER</span></span>	<span><span>22</span></span>	<span><span>3</span></span>	<span><span>2</span></span>	<span><span>Y</span></span>	<span><span><long></long></span></span>	<span><span>身高</span></span>
<span><span>WEIGHT</span></span>	<span><span>NUMBER</span></span>	<span><span>22</span></span>	<span><span>3</span></span>	<span><span>2</span></span>	<span><span>Y</span></span>	<span><span><long></long></span></span>	<span><span>体重</span></span>
<span><span>MEMO</span></span>	<span><span>BLOB</span></span>	<span><span>4000</span></span>	<span></span>	<span></span>	<span><span>Y</span></span>	<span><span><long></long></span></span>	<span><span>备注</span></span>

这样，我们在进行程序设计时，通过一条简单的SQL语句，然好通过Ole调用Word，便可为最终用户导出完整的数据库表字典文档。
再执行下列SQL语句:
select
    INDEX_NAME 索引名,INDEX_TYPE 索引类型,UNIQUENESS 索引类别
from
    user_indexes
where
    TABLE_NAME = ''''TABLE_TEST''''

得到结果如下(注：SYS_IL0000031226C00006$$索引为系统在创建数据库表时自动创建的，用于数据库表内容的维护):

<strong><span><span>　</span></span></strong>	<strong><span><span>索引名</span></span></strong>	<strong><span><span>索引类型</span></span></strong>	<strong><span><span>索引类别</span></span></strong>
<span><span>1</span></span>	<span><span>SYS_IL0000031226C00006$$</span></span>	<span><span>LOB</span></span>	<span><span>UNIQUE</span></span>
<span><span>2</span></span>	<span><span>TB_TEST_P_NAME</span></span>	<span><span>NORMAL</span></span>	<span><span>UNIQUE</span></span>

　

执行下列SQL语句，我们将得到更多的关于数据库表结构的信息：
select
    A.column_name 字段名,A.data_type 数据类型,A.data_length 长度,A.data_precision 整数位,
    A.Data_Scale 小数位,A.nullable 允许空值,A.Data_default 缺省值,B.comments 备注,
    C.IndexCount 索引次数
from
    user_tab_columns A,
    user_col_comments B,
    (select count(*) IndexCount,Column_Name from User_Ind_Columns where Table_Name = ''''TABLE_TEST'''' group by Column_Name) C
where
    A.Table_Name = B.Table_Name
    and A.Column_Name = B.Column_Name
    and A.Column_Name = C.Column_Name(+)
    and A.Table_Name = ''''TABLE_TEST''''

得到结果如下:

<strong><span><span>字段名</span></span></strong>	<strong><span><span>数据类型</span></span></strong>	<strong><span><span>长度</span></span></strong>	<strong><span><span>整数位</span></span></strong>	<strong><span><span>小数位</span></span></strong>	<strong><span><span>允许空值</span></span></strong>	<strong><span><span>缺省值</span></span></strong>	<strong><span><span>备注</span></span></strong>	<strong><span><span>索引次数</span></span></strong>
<span><span>BIRTHDAY</span></span>	<span><span>DATE</span></span>	<span><span>7</span></span>	<span></span>	<span></span>	<span><span>N</span></span>	<span><span><long></long></span></span>	<span><span>生日</span></span>	<span></span>
<span><span>HEIGHT</span></span>	<span><span>NUMBER</span></span>	<span><span>22</span></span>	<span><span>3</span></span>	<span><span>2</span></span>	<span><span>Y</span></span>	<span><span><long></long></span></span>	<span><span>身高</span></span>	<span></span>
<span><span>MEMO</span></span>	<span><span>BLOB</span></span>	<span><span>4000</span></span>	<span></span>	<span></span>	<span><span>Y</span></span>	<span><span><long></long></span></span>	<span><span>备注</span></span>	<span></span>
<span><span>NAME</span></span>	<span><span>VARCHAR2</span></span>	<span><span>40</span></span>	<span></span>	<span></span>	<span><span>N</span></span>	<span><span><long></long></span></span>	<span><span>姓名</span></span>	<span><span>1</span></span>
<span><span>SEX</span></span>	<span><span>VARCHAR2</span></span>	<span><span>1</span></span>	<span></span>	<span></span>	<span><span>N</span></span>	<span><span><long></long></span></span>	<span><span>性别</span></span>	<span></span>
<span><span>WEIGHT</span></span>	<span><span>NUMBER</span></span>	<span><span>22</span></span>	<span><span>3</span></span>	<span><span>2</span></span>	<span><span>Y</span></span>	<span><span><long></long></span></span>	<span><span>体重</span></span>	<span></span>

　

    当然Oracle数据字典的应用远不止这些，通过Oracle数据库字典的支持，我们可以得到Oracle数据库结构的所有信息，著名的数据库开发工具PL/SQL Developer完全就是基于Oracle的数据库字典实现的。