数据库的优化tips
数据库 TIPS：： 1、用于记录或者是数据分析的表创建时：：使用Id作为主键，1,2,3...表示消息条数，用户账号id用于做外键，一个用户对应唯一个accountId 一个accountId可以对应多条数据； 2、创建索引：： 例如需要根据注册版本号和注册游戏ID来查询另外一些
数据库 TIPS：：1、用于记录或者是数据分析的表创建时：：使用Id作为主键，1,2,3...表示消息条数，用户账号id用于做外键，一个用户对应唯一个accountId
一个accountId可以对应多条数据；
2、创建索引：： 例如需要根据注册版本号和注册游戏ID来查询另外一些字段的时候，就可以根据版本号和游戏ID来创建索引：：相当于就是根据查询条件来建索引；
3、数据库查询优化：： (1)、慎用 SELECT DISTINCT，从记录集中排除重复记录时，才使用DISTINCT;
(2)、选择最优效率的表名顺序 SQLSERVER从右到左的顺序处理FROM子句中的表名；当from子句中包含多个表的情况下，必须选择记录最少的表作为基础表，即把数据少的表放在最后；（注：有三个以上的表连接查询，则需要选择交叉表作为基础表）
4、使用表的别名（Alias）：：连接多个表是，使用别名把别名前缀于每个Column上
5、最好使用可SARG作为WHERE搜索条件：： 例如列和常量之间的比较。在WHERE子句里不可SARG的搜索条件如"IS NULL", "", "!=", "!>", "!
6、WHERE字句中的连接顺序：： SQLSERVER采用自下而上的顺序解析WHERE字句，所以表之间的连接必须写在其他WHERE条件之前，可以过滤最多数据记录的条件必须写在WHERE子句的末尾。
7、避免使用困难的正规表达式：：
8、 避免对大型数据表行数据的顺序存取：：
9、正确使用UNION和UNION ALL：： 使用UNION时、相当于在结果集上执行SELECT DISTINT，UNION将联合两个相类似的记录表，然后搜索重复的记录并排除；；； 如果搜索的联合记录集中木有重复记录，则使用UNION ALL。
10、EXISTS和IN的使用：： 基于基础表的查询中，为了满足一个条件，往往需要对另一个表进行连接，在这种情况下，使用EXISTS（或NOT EXISTS）通常将提高查询的效率。
11、用存储过程代替直接写查询语句：：减少网络流量和响应时间，提升应用程序性能；
12、存储过程名不要以sp_开头：：这个特别的前缀是为系统存储过程保留的，用户定义的存储过的运行，会稍微降低一些执行效率。
13、存储古城的拥有者要相同：： 同一存储过程里调用的所有对象的拥有者都应该相同，DBO更合适。
14、让食物尽可能的短：： 保持TSQL事务尽可能的短，这会减少锁的数量。
15、tinyint（0-255、-128 - 127 1字节）；smallint（0-65535、-32768 - 32767 2字节）
mediumint（0-16777215，-8388608 - 8388607 4字节）；int（0-4294967295、-2147483648 - 2147483647 8字节）
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