SQL Lite
SQL Lite
SQLite is a small C library that implements a self-contained, embeddable, zero-configuration SQL database engine.
It is a open source product and can be downloaded from http://www.sqlite.org/ . SQL Lite is best suited in Smart Client architecture, where we can locally store all our data in SQL Lite and then synchronize the local data with main database.
There is aslo a good Query analyzer clone at http://www.monkeyshinez.net/SQLiteQA/
An ADO.net Provider for SQLLite is available at http://sourceforge.net/projects/adodotnetsqlite/
SQL Lite下载(Precompiled Binaries For Windows):http://www.sqlite.org/sqlite-3_6_22.zip,
http://www.sqlite.org/download.html
相关文档:
一步一步学Linq to sql(一):预备知识
一步一步学Linq to sql(二):DataContext与实体
一步一步学Linq to sql(三):增删改
一步一步学Linq to sql(四):查询句法
一步一步学Linq to sql(五):存储过程
一步一步学Linq to sql(六):探究特性
一步一步学Linq to sql(七):并发与事务 ......
(1) 选择最有效率的表名顺序(只在基于规则的优化
器中有效):
Oracle
的
解析器按照从右到左的顺序处理from子句中的表名,from子句中写在最后的表(基础表 driving
table)将被最先处理,在from子句中包含多个表的情况下,你必须选择记录条数最少的表作为基础表。假如有3个以上的表连接查询,
那就 ......
-- create by zh
-- n 是作物的时间,x 是希望在几点成熟,返回播种的时间
with t as
(
select 64 n,9 x from dual union all
select 64 n,13 x from dual union all
select 64 n,17 x from dual union all
select 64 n,20 x from dual
)
select '成熟时间:' || lpad(to_char(n),4,' ' ......