一、获取表：

select table_name from user_tables; //当前用户的表      
select table_name from all_tables; //所有用户的表  
select table_name from dba_tables; //包括系统表
select table_name from dba_tables where owner='用户名'
select * from user_tab_comments where TABLE_NAME = 'T_CJ_ENTRUST_INFO';//查询表及表注释

user_tables：
table_name,tablespace_name,last_analyzed等

dba_tables：
ower,table_name,tablespace_name,last_analyzed等

all_tables：
ower,table_name,tablespace_name,last_analyzed等

all_objects：
ower,object_name,subobject_name,object_id,created,last_ddl_time,timestamp,status等

二、获取表字段：

select * from user_tab_columns where Table_Name='用户表';
select * from all_tab_columns where Table_Name='用户表';
select * from dba_tab_columns where Table_Name='用户表';

user_tab_columns：
table_name,column_name,data_type,data_length,data_precision,data_scale,nullable,column_id等

all_tab_columns ：
ower,table_name,column_name,data_type,data_length,data_precision,data_scale,nullable,column_id等

dba_tab_columns：
ower,table_name,column_name,data_type,data_length,data_precision,data_scale,nullable,column_id等

三、获取表注释：

select * from user_tab_comments
user_tab_comments：table_name,table_type,comments

相应的还有dba_tab_comments，all_tab_comments，这两个比user_tab_comments多了ower列。

四、获取字段注释：

select * from user_col_comments
user_col_comments：table_name,column_name,comments

五、总结（效果如图）

SELECT
    t.column_id,
    t.TABLE_NAME ,
    t.COLUMN_NAME ,
    c.COMMENTS ,
    t.DATA_TYPE ,
    t.DATA_LENGTH ,
    t.NULLABLE
FROM
    all_tab_columns t
INNER JOIN all_col_comments c ON
    t.TABLE_NAME = c.TABLE_NAME
    AND t.COLUMN_NAME = c.COLUMN_NAME
WHERE
    t.Table_Name = 'MS_TJYBZ01'
ORDER BY
    t.column_id ;

总结.png

六、查看表对应的数据量

SELECT t.table_name, t.num_rows FROM user_tables t WHERE NUM_ROWS IS NOT NULL AND TABLE_NAME NOT LIKE '%HIS%' ORDER BY NUM_ROWS DESC;

image.png

七、方案二，获取表注释

SELECT
     t.COLUMN_ID,
     t.COLUMN_NAME,
     u.COMMENTS,
     t.DATA_TYPE ,
     t.DATA_LENGTH ,
    DECODE( t.NULLABLE, 'N', 'TRUE', 'FALSE'),
     t.TABLE_NAME
FROM
    USER_TAB_COLUMNS  t
LEFT JOIN USER_COL_COMMENTS  u ON
     t.TABLE_NAME =  u.TABLE_NAME
    AND  t.COLUMN_NAME =  u.COLUMN_NAME
WHERE
     t.TABLE_NAME = 'T_CJ_ENTRUST_INFO'
ORDER BY
     t.COLUMN_ID ASC;

效果如图

image.png