ORACLE多表查询优化

心如止水_00

重点关注11:识别’低效执行’的SQL语句. 重点关注
用下列SQL工具找出低效SQL:
SELECT EXECUTIONS , DISK_READS, BUFFER_GETS,
         ROUND((BUFFER_GETS-DISK_READS)/BUFFER_GETS,2) Hit_radio,
         ROUND(DISK_READS/EXECUTIONS,2) Reads_per_run,
         SQL_TEXT
FROM    V$SQLAREA
WHERE   EXECUTIONS>;0
AND      BUFFER_GETS >; 0
AND (BUFFER_GETS-DISK_READS)/BUFFER_GETS < 0.8
ORDER BY 4 DESC;

心如止水_00

建表id为主键
create table table1(id number primary key,name varchar2(10));

建序列
create sequence seq_id start with 1 increment by 1;

检查当前值，或使序列增至下一个值
select seq_id.nextval from dual;

在插入语句中引用
insert into table1 values(seq_id.nextval,'tom');

心如止水_00

<a target="_blank" href="http://translate.google.com/translate_c?hl=en&sl=zh-CN&tl=en&u=http://blog.csdn.net/Matol">英语</a>



<a target="_blank" href="http://translate.google.com/translate_c?hl=en&sl=zh-CN&tl=ja&u=http://blog.csdn.net/Matol">日语</a>



<a target="_blank" href="http://translate.google.com/translate_c?hl=en&sl=zh-CN&tl=fr&u=http://blog.csdn.net/Matol">法语</a>





<a target="_blank" href="http://translate.google.com/translate_c?hl=en&sl=zh-CN&tl=ru&u=http://blog.csdn.net/Matol">俄语</a>

心如止水_00

http://wsp-java.iteye.com/blog/1603655

心如止水_00

http://caohuan346.iteye.com/blog/1604386

心如止水_00

sssssssssss

心如止水_00

ssssssssssssssssss

心如止水_00

ssssssssssssss

心如止水_00

http://www.iteye.com/blogs/subjects/Java_Collection

心如止水_00