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
