Decode functions in Oracle

Decode () can only create new columns (horizontal scaling), while the max () function is used to reduce the number of rows of the same category (vertical compression ), in this way, the original thin database record set is converted into a relatively flat matrix record set.
There are only four ways to reduce the number of records: Where, minus, grouping, distinct: Remember that the corresponding Oracle exists. in SQL, only select case end can be written ....

Select CP product, decode (LB, 'A', SL, null) a quantity, decode (LB, 'A', je, null) A amount,
Decode (LB, 'B', SL, null) Quantity of B, decode (LB, 'B', je, null) Amount of B,
Decode (LB, 'bing', SL, null) a quantity, decode (LB, 'bing', je, null) C amount,
Decode (LB, 'dd', SL, null) a quantity, decode (LB, 'dd', je, null) d Amount
From AAA;
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Product a quantity a amount B Amount B amount a amount C amount a amount d Amount
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Product A 1 2
Product B 2 3
Product c 3 4
Product D 1 4
Product A 2 6
Product c 3 6
Product E 4 5
Product A 5 4
Product D 6 4
Product B 1 3
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