贈oracle開發(fā)劍破冰山-全第13課oradev

劍破冰山之Oracle開發(fā)第13DATAGURU

2013法【】和幻燈片為煉數(shù)成金網(wǎng)絡課程的教學資料，所有資料只能在課程內(nèi)使用，不得在課程以外范圍散播，違者將可能被法律和經(jīng)濟課程詳 DATAGURU專業(yè)數(shù)據(jù)分 案DATAGURU專業(yè)數(shù)據(jù)分 計算連需求：將T表中X列的值逐個相乘，并輸出結果。X列的定義為NUMBER(5假定：最終乘積不會超過PLS_INTEGER解決方案rltforcur_tin(selectxfromend/DATAGURU專業(yè)數(shù)據(jù)分 計算連思路selectexp(sum(ln(x)))rltfrom但如果存在負數(shù)，怎么辦selectDATAGURU專業(yè)數(shù)據(jù)分 逐字重限制：原始記錄數(shù)不超過100條，每條記錄的str字段所含的字符數(shù)最多10數(shù)據(jù)提供withtas(select'AB'strfromdualunionselect'ABC'fromdualselect'AC'fromdualunionselect'ACB'from輸出結果為DATAGURU專業(yè)數(shù)據(jù)分 逐字重方法1：直接獲取每個字符，然后通過||withtas(select'AB'strfromdualunionselect'ABC'fromdualselect'AC'fromdualunionselect'ACB'fromfromDATAGURU專業(yè)數(shù)據(jù)分 逐字重方法2：拆分為單字符，然后重復，最后withtas(select'AB'strfromdualunionselect'ABC'fromdualselect'AC'fromdualunionselect'ACB'fromfrom(selectrownumid,strfromt)(selectlevelrnfromdualconnectbylevel<=(selectmax(length(str))fromt))groupby只適用于11g或以上版DATAGURU專業(yè)數(shù)據(jù)分 逐字重方法3：思路同方法withtas(select'AB'strfromdualunionselect'ABC'fromdualselect'AC'fromdualunionselect'ACB'fromt1as(selectid,str,rn,substr(str,rn,1)cfrom(selectrownumid,strfromt)(selectlevelrnfromdualconnectbylevel<=(selectmax(length(str))fromt)) t2as(selectid,str,sys_connect_by_path(c||c,',')conn_strfromt1startwithrn=1connectbyrn=priorrn+1andid=priorid)selectid,str,cast(replace(max(conn_str),',')asvarchar2(20))rltfromt2groupbyid,適用于9i和DATAGURU專業(yè)數(shù)據(jù)分 逐字重方法4：正則表withtas(select'AB'strfromdualunionselect'ABC'fromdualselect'AC'fromdualunionselect'ACB'fromDATAGURU專業(yè)數(shù)據(jù)分 分組求idnumbernotnullnamevarchar2(10)notagenumbernotsalarynumbernotsalary>15000andage>salary>15000andage<salary<15000andage>salary<15000andage<DATAGURU專業(yè)數(shù)據(jù)分 分組求select1type,count(*)fromtwheresalary>15000andage>select2,count(*)fromtwheresalary>15000andage<DATAGURU專業(yè)數(shù)據(jù)分 分組求selectsum(casewhensalary>15000andage>35then1else0sum(casewhensalary>15000andage<35then1else0DATAGURU專業(yè)數(shù)據(jù)分 分組求select……fromgroupbysign(salary-15000),sign(age-DATAGURU專業(yè)數(shù)據(jù)分 分組求withuas(selectcasewhensalary>15000andage>35thenwhen...thenwhen...thenwhen...thenendxfromselectx,count(*)fromugroupbyDATAGURU專業(yè)數(shù)據(jù)分 分組求withuascasewhensalary>15000casewhen...then1when...then2when...casewhen...then3when...then4endxfromselectx,count(*)fromugroupby比最樸素的思路2快30%左了解數(shù)據(jù)分布，可以合理安排條件，使sql運行DATAGURU專業(yè)數(shù)據(jù)分 分組求withras(selectsalary,age,count(*)cfromtgroupbysalary,uascasewhensalary>15000casewhen...then1when...then2when...casewhen...then3when...then4endx,cfromselectx,sum(c)fromugroupby以最小不重復的集合參與最后的復雜運算，是提高效率的最佳DATAGURU專業(yè)數(shù)據(jù)分 獨立

DATAGURU專業(yè)數(shù)據(jù)分 獨立 先后順序。所謂獨立樹，例如333444其實是111333-333444的一個分支，不視為獨立。上述數(shù)據(jù)應求得如下結果（子節(jié)點不區(qū)分先后順序

DATAGURU專業(yè)數(shù)據(jù)分 獨立逐行原始數(shù)據(jù)，從第一條記錄開始，將PID和ID都放入到一集合c1中，第二條記錄的PIDI和IDc1到和中DATAGURU專業(yè)數(shù)據(jù)分 獨立一條SQLDATAGURU專業(yè)數(shù)據(jù)分 獨立DATAGURU專業(yè)數(shù)據(jù)分 獨立DATAGURU專業(yè)數(shù)據(jù)分 自DATAGURU專業(yè)數(shù)據(jù)分 煉數(shù)成金逆 式網(wǎng)絡課Dataguru（煉數(shù)成金）是專業(yè)數(shù)據(jù)分 ，提供教育 ，內(nèi)容，社區(qū) 式網(wǎng)絡培訓課程模式。既繼承傳統(tǒng)教育重學習氛圍，重競爭壓力的特點，同時又發(fā)揮互聯(lián)網(wǎng)的打破時空限制，把天