（排班表一）使用SQL語句使數據從堅向排列轉化成橫向排列

知識重點：

1.extract(day from schedule01::timestamp)=13

Extract 屬於 SQL 的 DML（即數據庫管理語言）函數，同樣，InterBase 也支持 Extract，它主要用於從一個日期或時間型的字段內抽取年、月、日、時、分、秒數據，因此，它支持其關健字 YEAR、MONTH、DAY、HOUR、MINUTE、SECOND、WEEKDAY、YEARDAY。

　　Extract 的使用語法為：

　　 EXTRACT（關健字 FROM 日期或時間型字段）

　　如：extract(year from schedule01)=2017從日期中提取年份

2.max()函數：取最大值

3.case()函數的嵌套

　　注意嵌套case()函數時，每個case的開始和結束。 

 

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排班功能：現有兩個人員(A和B)，他們在不同日期的值班狀態(state)不同，現在要查詢他們在2017.6月的值班信息

表結構如下：

CREATE TABLE public.temp_schedule

(

  id integer NOT NULL DEFAULT nextval('temp_schedule_id_seq'::regclass),

  schedule01 timestamp without time zone,--日期

  schedule03 character varying(255),--姓名

  state character varying(255),--值班狀態(0休 1班)

  CONSTRAINT temp_schedule_pkey PRIMARY KEY (id)

)

 

1.查詢SQL語句：

select schedule03,schedule01,state  from temp_schedule

 where extract(year from schedule01)=2017 and extract(month from schedule01)=6

 order by  schedule03,schedule01;

顯示為：

 

 

2.現在需要根據(6月的)日期，從1號開始根據人員名稱橫向合並排列數據(即只顯示兩行)

顯示效果如下：

實現的SQL語句如下：

select schedule03 as name

,max(case when extract(day from schedule01::timestamp)=1 then state end) as day1

,max(case when extract(day from schedule01::timestamp)=2 then state end) as day2

,max(case when extract(day from schedule01::timestamp)=3 then state end) as day3

,max(case when extract(day from schedule01::timestamp)=4 then state end) as day4

,max(case when extract(day from schedule01::timestamp)=5 then state end) as day5

,max(case when extract(day from schedule01::timestamp)=6 then state end) as day6

,max(case when extract(day from schedule01::timestamp)=7 then state end) as day7

,max(case when extract(day from schedule01::timestamp)=8 then state end) as day8

,max(case when extract(day from schedule01::timestamp)=9 then state end) as day9

,max(case when extract(day from schedule01::timestamp)=10 then state end) as day10

,max(case when extract(day from schedule01::timestamp)=11 then state end) as day11

,max(case when extract(day from schedule01::timestamp)=12 then state end) as day12

,max(case when extract(day from schedule01::timestamp)=13 then state end) as day13

from temp_schedule

where extract(year from schedule01)=2017 and extract(month from schedule01)=6

group by schedule03;

 

3.將人員的值班狀態通過漢字(0休 1班)顯示出來，顯示效果如下：

SQL語句(主要是實現case的嵌套)：

select schedule03 as name

,max(case when extract(day from schedule01::timestamp)=1 then (case when state='0' then '休' else '班' end) end) as day1

,max(case when extract(day from schedule01::timestamp)=2 then (case when state='0' then '休' else '班' end) end) as day2

,max(case when extract(day from schedule01::timestamp)=3 then (case when state='0' then '休' else '班' end) end) as day3

,max(case when extract(day from schedule01::timestamp)=4 then (case when state='0' then '休' else '班' end) end) as day4

,max(case when extract(day from schedule01::timestamp)=5 then (case when state='0' then '休' else '班' end) end) as day5

,max(case when extract(day from schedule01::timestamp)=6 then (case when state='0' then '休' else '班' end) end) as day6

,max(case when extract(day from schedule01::timestamp)=7 then (case when state='0' then '休' else '班' end) end) as day7

,max(case when extract(day from schedule01::timestamp)=8 then (case when state='0' then '休' else '班' end) end) as day8

,max(case when extract(day from schedule01::timestamp)=9 then (case when state='0' then '休' else '班' end) end) as day9

,max(case when extract(day from schedule01::timestamp)=10 then (case when state='0' then '休' else '班' end) end) as day10

,max(case when extract(day from schedule01::timestamp)=11 then (case when state='0' then '休' else '班' end) end) as day11

,max(case when extract(day from schedule01::timestamp)=12 then (case when state='0' then '休' else '班' end) end) as day12

,max(case when extract(day from schedule01::timestamp)=13 then (case when state='0' then '休' else '班' end) end) as day13

from temp_schedule

where extract(year from schedule01)=2017 and extract(month from schedule01)=6

group by schedule03 ;

 

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