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发帖数: 1511 | 1 此帖太弱，大牛请略过。
两个月前做报表需要用outer join，当时一时未想起来。
Table1: Project
PID, PName
1, waterdatabase
2, raiseweibi
3, enjoyweibi
Table2:Task
PID, TID, TName
1, 1, create entry
1, 2, say hi
3, 1, use weibi saving
Report1: Report
PID+TID, PName, TName
1.1, waterdatabase, create entry
1.2, waterdatabase, say hi
2, raiseweibi,
3.1, enjoyweibi, use weibi saving
Report2: Summary
PID, PName, CountTask
1, waterdatabase, 2
2, raiseweibi, 0
3, enjoyweibi, 1
若不用outjoin，“2, raiseweibi,”就不在报表中。 |
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