单位距阵:
sql中行列转换:
Figure1
BookingNO Product Date Sum
1 A 11.01 100
2 A 12.01 200
3 B 12.11 30
4 A 12.17 1000
=>
Figure2
Product 11月 12月
A 100 1200
B 0 30
做法:
用笛卡尔积乘以Figure1
再通过分组合计得出Figure2
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