随机选择行的SQL语句? ORACLE SQLSERVER ECT.
MySQL:
SELECT column from table
ORDER BY RAND()
LIMIT 1
PostgreSQL:
SELECT column from table
ORDER BY RANDOM()
LIMIT 1
Microsoft SQL Server:
SELECT TOP 1 column from table
ORDER BY NEWID()
IBM DB2
SELECT column, RAND() as IDX
from table
ORDER BY IDX FETCH FIRST 1 ROWS ONLY
Thanks Tim
Oracle:
SELECT column from
( SELECT column from table
ORDER BY dbms_random.value )
WHERE rownum = 1
Thanks Mark Murphy
Feel free to post other example, variations, and SQL statements for other database servers in the comments.
相关文档:
oracle表空间操作详解
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3作者: 来源: 更新日期:2006-01-04
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7建立表空间
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9CREATE TABLESPACE data01
10DATAFILE '/ora ......
一、 常用日期数据格式
1.Y或YY或YYY 年的最后一位,两位或三位
SQL> Select to_char(sysdate,'Y') from dual;
TO_CHAR(SYSDATE,'Y')
--------------------
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SQL> Select to_char(sysdate,'YY') from dual;
TO_CHAR(SYSDATE,'YY')
---------------------
07
SQL> Select to_char(sysdate,'YYY') from d ......
在Stand alone的环境中创建Oracle data source供测试使用:
OracleDataSource dataSource = new OracleDataSource();
dataSource.setDriverType("oracle.jdbc.driver.OracleDriver");
dataSource.setURL("jdbc:oracle:thin:@localhost:1521:ORCL");
  ......
以system登录进去之后,执行下面的命令:
SQL> alter user scott account unlock; (完成解锁的操作)
用户已更改。
SQL> alter user scott identified by tiger; (重新给scott这个用户设定密码)
用户已更改。
SQL> conn scott/tiger
已连接。 ......
Oracle
1,shutdown之后,如何启动数据库实例?
通过CMD命令符 sqlplus "sys/password as
sysdba",会连到一个空闲实例,这样可再用startup命令。
2,装了数据库之后,用了shutdown,后用了startup等启动之后,可用sql
plus和网页方式连oracle。但用jdbc连接出错?
是监听器没启动:D:\oracle\product\10.1.0\Db_1\ ......