常用数据库sql总结(不断总结更新中)

1.统计表的列数

oracle:

select count(*) from USER_TAB_COLUMNS where table_name ='TABLE_NAME';//表名要大写

sqlserver:

select count(1) from syscolumns where id =object_id('table_name');

2.复制表结构

oracle:

create table dest_table_name as select * from src_table_name;

sqlsever:

select * into dest_table_name from src_table_name where 0=1

3.复制表结构以及表内数据

sqlserver:

select * into dest_table_name from src_table_name //适用于目标表不存在

insert into dest_table_name(fld1, fld2) select fld2, 5 from src_table_name //目标表必须存在

4.日期有关

sqlserver:

CONVERT(varchar(100), sys_time, 23) AS sys_time //截取年月日 ex.2009-03-08

CONVERT(varchar(7), sys_time, 23) AS sys_time //截取年月 ex.2009-03

select DATEPART(weekday,'2009-10-18') //统计日期在一周中的天数 周日为1 周六为7

select DATENAME(week, '2009-10-18') //统计日期在一年中的周数



//2009-12-30 和2010-1-1 虽然属于同一周 sqlserver把其按年份分割开来

select DATEPART(yy, '2009-12-30'),DATENAME(week, '2009-12-30') //输出:2009 53

select DATEPART(yy, '2010-1-1'),DATENAME(week, '2010-1-1') //输出:2010 1



按周统计的问题

--2009-10-18为周日

select DATEpart(week, '2009-10-18') ,DATEpart(weekday,'2009-10-18'); --2009年第43周的第1天

--2009-10-18为周日

set datefirst 1;

select DATEpart(week, '2009-10-18') ,DATEpart(weekday,'2009-10-18'); - -2009年的42周第7天



/*

* 统计数据的所属年份,所属周数,以及该周拥有几天的数据记录

*/

set datefirst 1;//设置星期一为一个星期第一天,sqlserver默认星期天为一个星期第一天

select T.msc_name,T.year,T.week,count(*) from

(SELECT

msc_name,

DATEPART(yy, sys_time) AS year,

DATEPART(week, sys_time) AS week,

DATEPART(weekday,sys_time) As weekday

FROM dbo.FUN_OMC_GSM_CELL_MSC_NAME

group by msc_name,DATEPART(yy, sys_time),DATEPART(week, sys_time),DATEPART(weekday,sys_time)

) T

group by T.msc_name,T.year,T.week

informix:

extend(systime,year to day)//2003-01-01

extend(systime,year to month)//2003-01

extend(systime,year to year)//2003

extend(current - 2 units minute) //当前时间减 2分钟



5.sql性能统计

sqlserver

declare @d datetime;

set @d=getdate();

--sql语句

select [语句执行花费时间(毫秒)]=datediff(ms,@d,getdate());



set statistics time on --统计时间

--sql

set statistics time off

set statistics io on --统计io

--sql

set statistics io off

6.其他

sqlserver

1.清除sqlserver缓存

DBCC FREEPROCCACHE;

DBCC DROPCLEANBUFFERS;

2.from 子查询

select * from ( select parent_id,count(*) as count from entity group by parent_id ) a

-- 子查询需要给统计列给别名,比如 count(*) 别名为count

3.sqlserver 分页方法一

-- 每页10条数据,第三页数据,按时间降序排列

SELECT *

FROM ( SELECT TOP 30 sysdate

from tb

where 1=1 group by sysdate order by sysdate desc ) temptb

where sysdate not in (select top 20 sysdate

from tb

where 1=1 group by sysdate order by sysdate desc )

order by sysdate desc

4.统计查询分页

SELECT *

FROM ( SELECT TOP 30 CONVERT(varchar(12),sysdate,112)+lac as pk, sysdate,lac,count(*) as count

from tb_demo

where 1=1 group by sysdate,lac order by sysdate desc,lac) tb

where pk not in (

select pk from

(select top 20 CONVERT(varchar(12),sysdate,112)+lac as pk, sysdate,lac

from tb_demo

where 1=1 group by sysdate ,lac order by sysdate desc,lac ) tb2 )

order by sysdate desc

7.常用oracle命令

//查看表结构

desc tab;

//显示当前用户的所有表

select tname from tab;

//查找sequence

select SEQUENCE_NAME from user_sequences;

//查看oracle数据库字符集

select userenv('language') from dual;

//改变sqlplus日期显示格式

alter session set NLS_DATE_FORMAT='YYYY-MM-DD HH24:MI:SS';

//建触发器

create or replace trigger iqcar_transfer_to_misc_user

after insert or update on user_order

for each row

declare

-- local variables here

dinnerid varchar2(10);

begin

dinnerid := '10086';

if inserting then

if ( trim(:New.Dinner_Id) = dinnerid) and ( trim(:New.State) = 'D01' ) then

insert into MISC_USER values (SEQ_MISC_USER_ID.NEXTVAL,:NEW.CELL_NUMBER,:New.Dinner_Id,:New.Order_Date,:NEW.STATE);

end if;

end if;

if updating then

if ( trim(:Old.Dinner_Id) = dinnerid) and ( trim(:New.State) = 'D10') then

insert into MISC_USER values (SEQ_MISC_USER_ID.NEXTVAL,:Old.CELL_NUMBER,:Old.Dinner_Id,:NEW.END_DATE,:New.STATE);

end if;

end if;

end transfer_to_misc_user;

//查找cell_number重复的所有记录

select * from user_order where cell_number in (select cell_number from cell_user_order group by cell_number having(count(*))>1)

//查看大字节类型数据内容

set long 2000;

//显示当前用户

show user ;

//设置sqlplus行长度

set linesize 1000;

//表复制

create table b as select * from iqcar_misc_user



// sqlplus执行多条sql

SET SERVEROUTPUT ON

--多条sql 在这

/ -- 用 / 表示结束

//查看触发器主题内容

set long 2000;

SET SERVEROUTPUT ON ;

select TRIGGER_BODY from user_triggers where TRIGGER_NAME ='MISC_USER';



//查看数据表锁

select lpad( ' ',decode(l.xidusn,0,3,0))||l.oracle_username User_name,

o.owner,o.object_name,o.object_type

from v$locked_object l,dba_objects o

where l.object_id=o.object_id

order by o.object_id desc ;

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;

//除去锁

alter system kill session '113,8359';

--查询sequence

select SEQUENCE_NAME from user_sequences where SEQUENCE_NAME like 'SEQ_IQCAR%';

show error; --显示错误

drop trigger trigger_name;

show user; --显示当前用户

sqlserver2005客户端访问:

58.19.183.230,1393 -- 格式如: IP,Port

//导出clob数据,user/passwd@servicename

exp govhubei/govhubei@govhubei

select dbms_lob.instr(ziduan ) from biao

//创建表空间 (plsql->command window)

create tablespace TSB datafile 'D:\oracle\temp\TSB.dbf' size 200m autoextend on next 10m maxsize unlimited;

alter database datafile 'D:\oracle\temp\TSB .dbf' autoextend on;

alter database datafile 'D:\oracle\temp\TSB .dbf' resize 220m;

//含大数据类型数据表的导入导出问题，比如 服务器A表空间TSA转移到服务器B表空间TSB

1.本地建TSB表空间 见上命令

2.拷贝TSA中的表到TSB中

create table TSB.dest_table_name as select * from TSA.src_table_name;

3.导出大数据类型表 用exp命令,目前所有数据表在表空间TSB下,见上命令

4.登录目的服务器B,导入到目的表空间



//导入dmp

imp user/passwd file=f:\jc_clob.dmp full=y

imp user/passwd file=f:\jc_clob.dmp full=y

imp user/password@db file = /home/wcity/jcw/jcw_server.dmp ignore=y full =y



//查看表所在表空间

select TABLESPACE_NAME from all_tables where table_name='TB_NEWS_CONTENT';

//查看TB开头的所有表

select tname from tab where tname like 'TB%'

//排序后的前100条记录

select * from (select * from tb t where t.category_id ='9' order by t.order desc) where rownum<=100;

//oracle表重命名

alter table TB_NEWS_CONTENT1 rename to TB_NEWS_CONTENT