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sql语句的优化。高分

热度:7347   发布时间:2013-02-25 21:19:19.0
sql语句的优化。。。高分求助
请高人把sql 性能 效率 优化下。。谢谢。。分全送。。
下面的city_id in(....) 这里数据是不同的,所以要多个sql union all 在一起,
比如sqlA如下:根据city_id 的范围不同还会有 同样的sql 需要union all 在一起。。求优化。


SQL code
select aa.fixed_net,aa.school_net,aa.differ_net,aa.wlan_net,aa.other_net,aa.city_name,aa.oneType_user,aa.twoType_user,aa.threeType_user,aa.other_user,aa.local_rom,aa.out_rom,aa.in_rom ,aa.nation_out_rom,aa.nation_in_rom from (select     'city_name' = '写死的',     'fixed_net' = sum(case a.id when 1 then a.num else 0 end ) ,    'school_net' = sum(case a.id when 3 then a.num else 0 end ),    'differ_net' = sum(case a.id when 4 then a.num else 0 end ),    'wlan_net' = sum(case a.id when 5 then a.num else 0 end ),    'other_net' = sum(case a.id when 0 then a.num else 0 end ),    'oneType_user' = sum(case b.id when 1 then b.num else 0 end ) ,    'twoType_user' = sum(case b.id when 2 then b.num else 0 end ),    'threeType_user' = sum(case b.id when 3 then b.num else 0 end ),    'other_user' = sum(case b.id when 99 then b.num else 0 end ),    'local_rom' = sum(case c.id when 0 then c.num else 0 end ),    'out_rom' = sum(case c.id when 1 then c.num else 0 end ),    'in_rom' = sum(case c.id when 2 then c.num else 0 end ),    'nation_out_rom' = sum(case c.id when 3 then c.num else 0 end ),    'nation_in_rom' = sum(case c.id when 5 then c.num else 0 end )     from      (select count(user_id) as num,certify_user_type as id         from ${tableName} where certify_user_type not in (2) and city_id in ('001','002','003') //此处的数据是动态的        group by certify_user_type    ) a     ,       ( select count(user_id) as num ,user_type_id as id         from ${tableName}         where user_type_id in (1,2,3,99) and certify_user_type=2 and city_id in ('001','002','003')         group by user_type_id    ) b     ,     ( select count(user_id) as num,romflag as id         from ${tableName} where city_id in ('001','002','003')         group by romflag    ) c) aa


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可以试下minus~ 来代替in或者是not in
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需要了解更多的问题:
1、 你这个语句,a、b、c 三张表是直接 笛卡尔 连接(无连接条件)?
2、 a、b、c 三张表所选择出来的数据行大约有多少行?
3、 city_id in ('001','002','003') 里面的值大约有多少个?

两个稍微复杂点的问题:
1、 ${tableName} 索引是怎么建的?
2 、这个SQL的执行计划是怎么样的?
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我是来看看我的等级的!!!
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楼主应该发到数据库栏目中,那里数据库高手比较多。
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用in的效率都是非常低的哈,最好不要用in 可以考虑数据库的设计,或者其他函数来实现,
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首先,a b c 3个表没有关联条件,那就是3个表交叉组合
其次,a b c 3个表的检索相似,没有必要特意写成3个表,直接和在一个就可以了

SQL code
select     'city_name' = '写死的',     'fixed_net' = sum(case certify_user_type when 1 then 1 else 0 end ) ,    'school_net' = sum(case certify_user_type when 3 then 1 else 0 end ),    'differ_net' = sum(case certify_user_type when 4 then 1 else 0 end ),    'wlan_net' = sum(case certify_user_type when 5 then 1 else 0 end ),    'other_net' = sum(case certify_user_type when 0 then 1 else 0 end ),    'oneType_user' = sum(case when user_type_id=1 and certify_user_type<>2 then 1 else 0 end ) ,    'twoType_user' = sum(case when user_type_id=2 and certify_user_type<>2 then b.num else 0 end ),    'threeType_user' = sum(case when user_type_id=3 and certify_user_type<>2 then 1 else 0 end ),    'other_user' = sum(case when user_type_id=99 and certify_user_type<>2 then 1 else 0 end ),    'local_rom' = sum(case romflag when 0 then 1 else 0 end ),    'out_rom' = sum(case romflag when 1 then 1 else 0 end ),    'in_rom' = sum(case romflag when 2 then 1 else 0 end ),    'nation_out_rom' = sum(case romflag when 3 then 1 else 0 end ),    'nation_in_rom' = sum(case romflag when 5 then 1 else 0 end )     from  ${tableName}   where city_id in ('001','002','003') --你的动态条件
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