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[数据库]Oracle小知识


常用查看表结构命令

elect 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' 

 

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 

 

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 

 

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。 

 

获取字段注释: 

 

select * from user_col_comments 

 

user_col_comments:table_name,column_name,comments

 

查询表空间容量大小,为表空间添加dbf文件

  Select

     file_id,

     file_name,

     tablespace_name,

     autoextensible,increment_by,

     bytes/1024/1024 "bytes MB",

     maxbytes/1024/1024 "maxbytes MB" ,

     bytes/maxbytes

  from   dba_data_files

  order by file_id desc;

 

  alter tablespace 表空间

  add datafile 'dbf文件物理路径' size 20m reuse

    autoextend on

    next 5M

select * from sys.props$ where name ='NLS_CHARACTERSET';

查询字符集

 

SELECT object_name, s.sid, s.serial#, p.spid

  FROM v$locked_object l, dba_objects o, v$session s, v$process p

 WHERE l.object_id = o.object_id

   AND l.session_id = s.sid

   AND s.paddr = p.addr;

查询死锁

alter system kill session 'sid,serial#';  

杀掉进程

select * from v$version

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