IT技术的专栏

一.数据导出数据的导出：pg_dump -U postgres(用户名)  (-t 表名)  数据库名(缺省时同用户名)  > c:\fulldb.sql举例：数据库导出   Pg_dump -U postgres [-t(表名)] 数据库名 >C:\A.sql二.取消口令输入操作@echo offSet PGPASSWORD=postgresPg_dump -U

1、以下方法只能获取当前年份：       select   to_char(current_date,'yyyy')  为 character varying格式类型     select extract(year from now())  为double precision 格式类型     select to_char((SELECT now()::timestamp),'yyy

TO_NUMBER用法Oracle -- SELECT COL1 FROM A_TABLE ORDER BY TO_NUMBER(COL1)Postgresql- select TO_NUMBER(COL1,'99G999D9S') from A_TABLE [注：'999999' ---- 6位数为COL1字段的长度]

SQL中遇到多条相同内容只取一条的最简单实现如下：表timeandselect * from timeand as a where not exists(select 1 from timeand where a.time = time and a.total