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Oracle advanced sql by dj mailto:dingjunlove@163.com
第 3 页 共 90 页
目 录
1.集合操作··········································································································· 5
1.1.UNION 和 UNION ALL ························································································· 5
1.2.INTERSECT 交集操作 ························································································ 6
1.3. MINUS 差集操作····························································································· 6
1.4.集合操作实例································································································ 7
2.EXISTS 和 NOT EXISTS 的使用 ············································································ 9
2.1. EXISTS 的使用 ······························································································· 9
2.2 NOT EXISTS 的使用························································································· 10
3.WITH 子句·······································································································11
3.1 WITH 基础 ····································································································11
3.2 11G R2WITH 新特性······················································································· 16
3.3 WITH 对执行计划的影响 ················································································· 16
4.MERGE INTO 合并资料····················································································· 17
5.层次查询(HIERARICAL RETRIVAL)···································································· 20
6.DECODE 函数和行列互换 ·················································································· 32
7.CASE 表达式 ··································································································· 40
7.1 CASE 简介 ··································································································· 40
7.2 两种 CASE ·································································································· 41
7.3 综合实例 ··································································································· 42
8.ROWNUM—TOP-N 分析 ··················································································· 44
9.相关子查询和非相关子查询 ················································································· 49
10.增强的 GROUP BY ·························································································· 50
11.分析函数(ANALYTICAL FUNCTIONS)································································ 51
11.1 背景知识·································································································· 51
11.2 分析函数基础···························································································· 51
11.3 分析函数的使用························································································· 60
12.ROWID 的使用······························································································· 71
13. ORACLE10G 正则表达式 ················································································· 71
14.使用 HINT ····································································································· 71
15.PARITION 分区 ······························································································ 71
16.并行操作 ······································································································· 71
17.扩展 DDL 和 DML 语句 ···················································································· 72
Oracle advanced sql by dj mailto:dingjunlove@163.com
第 4 页 共 90 页
17.1 背景和目标······························································································· 72
17.2 经常使用的扩展························································································· 72
17.3 向多个目标 INSERT ······················································································ 73
17.4 EXTERNAL TABLES(外部表) ············································································· 77
18.MODEL 语句 ································································································· 78
19.10G 闪回查询 ································································································· 78
20.专题—行列转换 ······························································································ 78
21.专题—连续值和累计值问题················································································ 78
22.专题—NULL 和 DUAL 详解··············································································· 79
22.1 NULL 详解 ································································································· 79
22.1.1 null
基本知识
················································································································ 79
23.专题—时间、数字、字符格式详解······································································· 84
24.专题—ORACLE 字符集问题 ·············································································· 86
25.专题-随机值查询 ····························································································· 86
25.1 DBMS_RANDOM 包 ··················································································· 86
25.2 SYS_GUID 函数···························································································· 88
25.3 SAMPLE 查询 ······························································································ 89
25.4 使用例子·································································································· 89
Oracle advanced sql by dj mailto:dingjunlove@163.com
第 5 页 共 90 页
1.集合操作
目标:学习 oracle 中集合操作的有关语句,掌握 union,union all,minus,interest
的使用,能够描述集合运算,并且能够将多个查询组合到一个查询中去,能够控
制行返回的顺序。
包含集合运算的查询称为复合查询。见表格1-1
表1-1
Operator Returns content
UNION
由每个查询选择的所有
不重复的行
并集不包含重复值,默认
按第 1 个查询的第 1 列升
序排列
UNION ALL
由每个查询选择的所有
的行,包括所有重复的行
包括所有重复的行 完全
并集包含重复值,不排序
INTERSECT
由每个查询选择的所有
不重复的相交行
交集,不包含重复行,按
第 1 个查询的第 1 列升序
排列
MINUS
在第一个查询中,不在后
面查询中的行
不包含重复行,按第 1 个
查询的第 1 列升序排列
所有的集合运算与等号的优先级相同,如果 SQL 语句包含多个集合运算并
且没有圆括号明确地指定另一个顺序,Oracle 服务器将以从左到右的顺序计算。
你应该使用圆括号来明确地指定带另外的集合运算的 INTERSECT (相交) 运算
查询中的赋值顺序。所有集合操作都不忽略 null<查询的行的所有列都为 null>。
Union all 效率一般比 union 高。Union all 内部不做排序工作,也不做剔除
重复行工作,而 union 则做这个工作。
1.1.union 和 union all
UNION(联合)运算
UNION运算返回所有由任一查询选择的行。用UNION运算从多表返回所有行,
但除去任何重复的行。
原则 :
À 被选择的列数和列的数据类型必须是与所有用在查询中的SELECT语句
一致。列的名字不必相同。
À 联 合运算在所有被选择的列上进行。
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- zeroxiaozou2013-03-01不错的资料,对深入理解SQL有帮助
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