文件名称：Oracle+SQL大全解析
文件大小：154KB
文件格式：PDF
更新时间：2016-04-23 04:47:05
Oracle+SQL
数据库语言解析 各种数据库的流程 目录........................................................................................................................................ 2 第 1章 模块功能概要描述................................................................................................... 4 第 2章 SQL 语句编写注意问题 .......................................................................................... 5 2.1 IS NULL 与 IS NOT NULL.................................................................................... 5 2.2 联接列...................................................................................................................... 5 2.3 带通配符（%）的 like语句 .................................................................................. 6 2.4 Order by 语句 ...................................................................................................... 6 2.5 NOT......................................................................................................................... 6 2.6 IN 和 EXISTS........................................................................................................ 7 第 3章 SQL 语句性能优化 .................................................................................................. 9 3.1 选用合适的 ORACLE 优化器................................................................................ 9 3.2 访问 Table的方式................................................................................................... 9 3.3 共享 SQL 语句...................................................................................................... 10 3.4 选择最有效率的表名顺序(只在基于规则的优化器中有效)............................. 11 3.5 WHERE 子句中的连接顺序................................................................................. 12 3.6 SELECT子句中避免使用 ‘ *’ ............................................................................. 13 3.7 减少访问数据库的次数........................................................................................ 13 3.8 使用 DECODE 函数来减少处理时间.................................................................. 14 3.9 整合简单,无关联的数据库访问........................................................................... 15 3.10 删除重复记录...................................................................................................... 16 3.11 用 TRUNCATE 替代 DELETE.......................................................................... 16 3.12 尽量多使用 COMMIT........................................................................................ 16 3.13 计算记录条数...................................................................................................... 17 3.14 用 Where子句替换 HAVING子句.................................................................... 17 3.15 减少对表的查询.................................................................................................. 17 3.16 通过内部函数提高 SQL 效率............................................................................ 18 3.17 使用表的别名(Alias) .......................................................................................... 20 3.18 用 EXISTS替代 IN............................................................................................. 20 3.19 用 NOT EXISTS 替代 NOT IN........................................................................... 21 3.20 用表连接替换 EXISTS....................................................................................... 21··············································································································································