Oracle SQL优化技巧

一、链接：

ORACLE多表查询优化

oracle的 分表 详解 -----表分区

Oracle数据库查询优化方案（处理上百万级记录如何提高处理查询速度）

数据库SQL优化大总结之 百万级数据库优化方案

解决模糊查询速度慢问题(ORACLE)

二、首先最重要的是要看懂Oracle执行计划分析SQL

https://www.cnblogs.com/Dreamer-1/p/6076440.html

1、rownum

(1)

SELECT ywlsdm, qybm, spzt, czsj, czrydm FROM GH_hs WHERE ywlsdm in (SELECT ywlsdm FROM GH_hs WHERE spzt = '2')

2、with as 临时表

select * from ( with qybm as ( select gx.qybm from (select a.ghdm from gh_ghdm a start with a.ghdm = '1' connect by prior a.ghdm = a.sjghdm) gh inner join gh_qyghgx gx on gh.ghdm = gx.tjghdm ), yg as ( select * from gh_jc_yg t where t.yglx = '0' ) select yg.* from qybm , yg where qybm.qybm = yg.qyghdm )

 3、索引

转载于:https://www.cnblogs.com/ssbydk/p/9364480.html