oracle行转列
select i.sid,i.sname,i.birthday,i.schooltime,i.sphone,c.classname,a.assnname,sum(decode(subject,'语文',s.score,0)) as chin,
sum(decode(subject,'数学',s.score,0)) as math,
sum(decode(subject,'英语',s.score,0)) as eng from student_info i
left join student_expand e on i.sid = e.sid left join student_class c on
c.classid = e.classid left join student_assn a on a.assnid = e.assnid left join student_score s on s.sid = i.sid
group by i.sid,i.sname,i.birthday,i.schooltime,i.sphone,c.classname,a.assnname;
行转列:
decode(subject,'数学',s.score,0) 用法:如果subject会等于数学 ,则最后值等于 s.score 否则值等于: 0
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1import java.sql.*;
2import java.util.logging.Level;
3import java.util.logging.Logger;
4
5/** *//**
6 * Title: JDBC连接数据库
7 * Description: 本实例演示如何使用JDBC连接Oracle数据库，并演示添加数据和查询数据.
8 */
9public class JDBCExampl ......
一个使用ibatis对数据库增删改查的例子:
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ibatis-dao-2.jar,ibatis-sqlmap-2.jar,mysql包是mysql-connector-java-5.0.3-bin.jar.
步骤:
1.创建数据库:
create database itcast;
use itcast;
创建表：
create table stu ......
Exam Number/Code : 1Z0-053
Exam Name : Oracle Database 11g: Administration II
Questions and Answers : 167 Q&As
Update Time: 2010-05-15
1. You are not sure if Flashback Database is enabled. What database column and view can you query to
see if the flashback logs are being created in the ......
SQL中的单记录函数
1.ASCII
返回与指定的字符对应的十进制数;
SQL> select ascii(A) A,ascii(a) a,ascii(0) zero,ascii( ) space from dual;
A A ZERO SPACE
--------- --------- --------- ---------
65 97 48 32
2.CHR
给出整数,返回对应的字符;
SQL> select chr(54740) zhao,chr(65) chr65 from dual;
......
oracle中使用on delete cascade和on delete set null来建立外键
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