Oracle查询一个用户的所有表的结构信息的SQL语句

选择出的信息结果：表名 说明

select user_tab_comments.table_name as 表名,user_tab_comments.comments as 说明 from user_tab_comments

选择出的信息结果：表名（备注）、列名、列标注、主键、外键、字段类型、长度、小数位数、是否允许空、默认值

select
           case
                when user_tab_comments.comments is null then a.table_name
                  else a.table_name||'('||user_tab_comments.comments||')'
           end as 表名（备注）,
           a.column_name as 列名,
           f.comments as 列标注,
           decode(e.key1, 'P', '√', '') as 主键,
           decode(e.key2, 'R', '√', '') as 外键,
           a.data_type as 字段类型,
           NVL(decode(a.data_type, 'NUMBER', a.data_precision, a.data_length),0) as 长度,
           NVL(a.data_scale,0) as 小数位数,
           a.nullable as 是否为空,
           a.data_default as 默认值
      from
           user_tab_columns a,
            user_col_comments f,
           user_tab_comments,
           ( select
                   uc.table_name,
                    uc.constraint_name,
                   ucc.column_name,
                   uc.constraint_type key1,
                   uc.constraint_type key2
             from
                      user_constraints uc,
                      user_cons_columns ucc
                where
                      (uc.constraint_type='R'or uc.constraint_type='P')
               and uc.constraint_name=ucc.constraint_name
                  and uc.owner=ucc.owner
                  and uc.table_name=ucc.table_name
                  and ucc.table_name not like 'BIN$%==$0'
           ) e
      where
              a.table_name = e.table_name(+)
              and a.column_name = e.column_name(+)
              and a.table_name = f.table_name
              and a.column_name = f.column_name
              and a.table_name = user_tab_comments.table_name
              and a.table_name not like 'BIN$%==$0'
      order by a.table_name