資料庫之行轉列與列轉行方法
阿新 • • 發佈：2018-12-31
--建立縱表TABLE_A
| CREATE TABLE TABLE_A ( NAME VARCHAR2(20), SUBJECT VARCHAR2(20), SCORE NUMBER(22,0)); |
--向表TABLE_A中插入資料
| INSERT INTO TABLE_A (NAME, SUBJECT, SCORE) VALUES ('張三', '語文', 60); INSERT INTO TABLE_A (NAME, SUBJECT, SCORE) VALUES ('張三', '數學', 70); INSERT INTO TABLE_A (NAME, SUBJECT, SCORE) VALUES ('張三', '英語', 80); INSERT INTO TABLE_A (NAME, SUBJECT, SCORE) VALUES ('李四', '語文', 90); INSERT INTO TABLE_A (NAME, SUBJECT, SCORE) VALUES ('李四', '數學', 100); |
插入資料後TABLE_A如下圖：
--建立縱表TABLE_B
| CREATE TABLE TABLE_B ( NAME VARCHAR2(20), CHINESE NUMBER(22,0), MATH NUMBER(22,0), ENGLISH NUMBER(22,0)); |
--向表TABLE_B中插入資料
| INSERT INTO TABLE_B (NAME, CHINESE, MATH, ENGLISH) VALUES ('張三', 60, 70, 80); INSERT INTO TABLE_B (NAME, CHINESE, MATH, ENGLISH) VALUES ('李四', 90, 100, 0); |
--縱錶轉橫表 TABLE_A-->TABLE_B
--方法一：使用case ... when ... then ... else ... end 函式
| select name, sum (case subject when '語文' then score else 0 end) as chinese, sum (case subject when '數學' then score else 0 end) as math, sum (case subject when '英語' then score else 0 end) as english from Table_A group by name |
--方法二：使用pivot
| select * from Table_A pivot (max(score)for subject in('語文','數學','英語')) |
--橫錶轉縱表 TABLE_B-->TABLE_A
--方法一：使用union all
| select NAME,'語文' as SUBject,chinese as score from Table_B union all select NAME,'數學' as SUBject,math as score from Table_B union all select NAME,'英語' as SUBject,english as score from Table_B order by name,subject desc |
--方法二：使用unpivot
| select name,subject,score from Table_B unpivot (score for subject in (chinese,math,english)) |