Oracle分栏(非分页)查询-编程知识

Oracle分栏(非分页)查询

不知道Oracle怎么进行数据分栏(分栏: 因数据列过长, 部分数据作为新列显示). 在这里先记录一下粗浅的查询方法.
数据源例子:

    select '日用百货' as cat, '手电筒' as name, 20 as amount, '2024-01-27' as dt from dualunion allselect '餐饮美食' as cat, '鸡公煲' as name, 15.9 as amount, '2024-01-27' as dt from dualunion allselect '餐饮美食' as cat, '海带粉' as name, 6 as amount, '2024-01-27' as dt from dualunion allselect '日用百货' as cat, '垃圾桶' as name, 9.9 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '大铁锅' as name, 66 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '电火锅' as name, 216 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '电饭锅' as name, 166 as amount, '2024-01-26' as dt from dualunion allselect '餐饮美食' as cat, '老乡鸡' as name, 19.9 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '塑料小板凳' as name, 8 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '垃圾袋' as name, 7.5 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '塑料靠背凳' as name, 10 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '鞋刷' as name, 4 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '撑衣杆' as name, 8.5 as amount, '2024-01-26' as dt from dualunion allselect '餐饮美食' as cat, '海带粉' as name, 6 as amount, '2024-01-26' as dt from dual

思路: 创造提取新列的条件, 然后进行关联查询

with t as (select '日用百货' as cat, '手电筒' as name, 20 as amount, '2024-01-27' as dt from dualunion allselect '餐饮美食' as cat, '鸡公煲' as name, 15.9 as amount, '2024-01-27' as dt from dualunion allselect '餐饮美食' as cat, '海带粉' as name, 6 as amount, '2024-01-27' as dt from dualunion allselect '日用百货' as cat, '垃圾桶' as name, 9.9 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '大铁锅' as name, 66 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '电火锅' as name, 216 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '电饭锅' as name, 166 as amount, '2024-01-26' as dt from dualunion allselect '餐饮美食' as cat, '老乡鸡' as name, 19.9 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '塑料小板凳' as name, 8 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '垃圾袋' as name, 7.5 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '塑料靠背凳' as name, 10 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '鞋刷' as name, 4 as amount, '2024-01-26' as dt from dualunion allselect '日用百货' as cat, '撑衣杆' as name, 8.5 as amount, '2024-01-26' as dt from dualunion allselect '餐饮美食' as cat, '海带粉' as name, 6 as amount, '2024-01-26' as dt from dual
)
, tmd as (select p.*, ceil(p.rn/3) as dv, mod(p.rn, 3) as mdfrom (select row_number() over (partition by cat order by dt,amount desc) as rn, t.*from t) p
)
select t1.cat, t1.name as name1,t1.amount as amount1, t2.name as name2,t2.amount as amount2, t3.name as name3,t3.amount as amount3
from (select * from tmd where md=1) t1
left join (select * from tmd where md=2) t2 on t1.cat=t2.cat and t1.dv=t2.dv
left join (select * from tmd where md=0) t3 on t1.cat=t3.cat and t1.dv=t3.dv
order by t1.cat,t1.dv,t1.md
;

查询结果:

CAT	NAME1	AMOUNT1	NAME2	AMOUNT2	NAME3	AMOUNT3
日用百货	电火锅	216	电饭锅	166	大铁锅	66
日用百货	塑料靠背凳	10	垃圾桶	9.9	撑衣杆	8.5
日用百货	塑料小板凳	8	垃圾袋	7.5	鞋刷	4
日用百货	手电筒	20	NULL	NULL	NULL	NULL
餐饮美食	老乡鸡	19.9	海带粉	6	鸡公煲	15.9
餐饮美食	海带粉	6	NULL	NULL	NULL	NULL