最近写的功能中有这样一个小功能，根据数据库查询此库中是否有某表，如果有，查询某表下面的某个字段的详细信息

 其中一种是...

select ATC.OWNER,

       atC.TABLE_NAME,

       ATC.COLUMN_NAME,

       ATC.DATA_TYPE,

       ATC.DATA_LENGTH,

       ATC.NULLABLE,

       ucc.comments

  from (select ATC.OWNER,

               atC.TABLE_NAME,

               ATC.COLUMN_NAME,

               ATC.DATA_TYPE,

               ATC.DATA_LENGTH,

               ATC.NULLABLE

          from all_tab_columns ATC

         where ATC.TABLE_NAME = '要查询的字段名'

           and ATC.COLUMN_NAME in ('要查询的字段名','要查询的字段名','要查询的字段名')) atc

  left outer join user_col_comments ucc on atc.table_name = ucc.table_name

                                       and atc.column_name =

                                           ucc.column_name

  left outer join user_tab_comments utc on atc.table_name = utc.table_name

 order by atc.table_name, atc.column_name;

 1 SELECT USER_TAB_COLS.TABLE_NAME   as 表名,

 2        USER_TAB_COLS.COLUMN_NAME  as 列名,

 3        USER_TAB_COLS.DATA_TYPE    as 数据类型,

 4        USER_TAB_COLS.DATA_LENGTH  as 长度,

 5        USER_TAB_COLS.NULLABLE     as 是否为空,

 6        USER_TAB_COLS.COLUMN_ID    as 列序号,

 7        user_col_comments.comments as 备注

 8   FROM USER_TAB_COLS

 9  inner join user_col_comments on user_col_comments.TABLE_NAME =

10                                  USER_TAB_COLS.TABLE_NAME

11                              and user_col_comments.COLUMN_NAME =

12                                  USER_TAB_COLS.COLUMN_NAME    where  user_col_comments.TABLE_NAME='数据库名' AND  USER_TAB_COLS.COLUMN_NAME in ('要查询的字段名','要查询的字段名','要查询的字段名')

13

 select

      ut.COLUMN_NAME,--字段名称

      uc.comments,--字段注释

      ut.DATA_TYPE,--字典类型

      ut.DATA_LENGTH,--字典长度

      ut.NULLABLE--是否为空

from user_tab_columns  ut

inner JOIN user_col_comments uc

on ut.TABLE_NAME  = uc.table_name and ut.COLUMN_NAME = uc.column_name

where ut.Table_Name='某表名'

order by ut.column_name