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多值多慮
累計稅
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下次學查看全部
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@MySQL---計算累進稅
select?user_name,sum(curmoney*rate)?as?taxmoney from( ????select?user_name,money,low,high, ????least(money-low,high-low)?as?curmoney,rate ????from?user1?a? ????join?taxrate?b?on?a.money>b.low)?a group?by?user_name
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@MySQL---使用GROUP BY實現多屬性查詢
select?a.user_name? from?user1?a? join?user1_skills?b?on?a.id=b.user_id? where?b.skill?in?('念經','變化','騰云','浮水')?and?b.skill_level>0? group?by?a.user_name?having?count(*)>=2;查看全部 -
@MySQL---使用關聯方式實現多屬性查詢
Select?a.user_name,b.skill,c.skill,e.skill?From?user1?a From?user1?a? Left?join?user1_skill?b?on?a.id?=b.user_id?and?b.skill='念經'?and b.skill?level>0 Left?join?user1_skill?c?on?a.id?=?c.user_id?and?c.skill='變化'?and c.skill_level>0 Left?join?user1_skill?d?on?a.id?=?d.user_id?and?d.skill?=?'騰云'?and c.skill_level>0 Left?join?user1_skill?e?on?a.id?=?e.user_id?and?e.skill?=?'浮水'?and e.skill_level>0 Where?(case?when?b.skill?is?not?null?then?1?else?0?end) +(case?when?c.skill?is?not?null?then?1?else?0?end) +(case?when?d.skill?is?not?null?then?1?else?0?end) +(case?when?e.skill?is?not?null?then?1?else?0?end)>=2;
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@MySQL---同一屬性的多值過濾
方式一
select?a.user_name,b.skill,b.skill_level from?user1?a?join?user1_skills?b?on?a.id?=b.user_id where?skill?in?('變化','念經')?and?skill_skill>0;方式二
select?a.user_name,b.skill,c.skill? from?user1?a?join?user1_skills?b?on?a.id=b.user_id?and?b.skill='念經'? join?user1_skills?c?on?c.user_id=b.user_id?and?c.skill='變化'? where?b.skill_level>0?and?c.skill_level>0;
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@MySQL---獨有的多例過濾方式
SELECT?a.user_name,b.timerstr,kills FROM?user1?a JOIN?user_kills?b?ON?a.id=b.user_id WHERE(b.user_id,b.kills)?IN( SELECT?user_id,MAX(kills) FROM?user_kills GROUP?BY?user_id);
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select?user_name?from?user1?where?id?in?(select?user_id?from?user_kills); --?使用子查詢可以避免由于子查詢中的數據產生的重復。
select?a.user_name?from?user1?a?join?user_kills?b?on?a.id?=b.user_id; --?會產生重復記錄
select?distinct?a.user_name?from?user1?a?join?user_kills?b?on?a.id?=b.user_id; --?使用distinct去除重復記錄
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子杳查詢語句:select user_name（列名） from user1（表名） where id in（select user_id（列名）from uers（表名））查看全部
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子杳查詢語句:select user_name（列名） from user1（表名） where id in（select user_id（列名）from uers（表名））查看全部
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上節沒實現查看全部
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上節沒實現 而且左連接不懂查看全部
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沒實現查看全部
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上節沒實現
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