常用SQL整理

1、添加一个或多个字段：

alter table tableName add column1 int(12) DEFAULT NULL;

alter table tableName add (column1 int(12) DEFAULT NULL, column2 float(12,2) DEFAULT 0, column3 varchar2(10) DEFAULT null, ...);

 

2、删除一个或多个字段：

alter table tableName drop column1;

alter table tableName drop (column1, column2, column3, ...);

 

3、更新字段：

update tableName set column1=1, column2=1, ... where condition;

 

4、添加表、字段注释：

comment on table tableName is '***';

comment on column tableName.columnName is '***';

 

5、锁表查询：

select sess.sid, sess.serial#, lo.oracle_username, lo.os_user_name, ao.object_name, lo.locked_mode from v$locked_object lo, dba_objects ao, v$session sess 
where ao.object_id = lo.object_id and lo.session_id = sess.sid;

 

6、查看oracle字符集

select userenv('language') from dual;

 

7、数据库操作