一、创建score_表,并插入数据
CREATE TABLE SCORE_1 (SNO VARCHAR2(10) NOT NULL, CNAME VARCHAR2(20) NOT NULL, SCORE NUMBER NOT NULL); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (103,'CHINESE',86); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (105,'CHINESE',75); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (109,'CHINESE',68); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (103,'MATH',92); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (105,'MATH',88); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (109,'MATH',76); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (103,'ENGLISH',64); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (105,'ENGLISH',91); INSERT INTO SCORE_1(SNO,CNAME,SCORE)VALUES (109,'ENGLISH',78);
二、创建score_2表,并插入数据
create table ( sno VARCHAR2(10) not null, 语文 VARCHAR2(20) not null, 数学 VARCHAR2(20) not null, 英语 VARCHAR2(20) not null ); INSERT INTO SCORE_58 VALUES (103,86,92,64); INSERT INTO SCORE_58 VALUES (105,75,88,91); INSERT INTO SCORE_58 VALUES (109,68,76,78);
三、score_1==>score_2
1.case when
SELECT SNO, MAX(CASE WHEN CNAME = 'CHINESE' THEN SCORE ELSE 0 END) 语文, MAX(CASE WHEN CNAME = 'MATH' THEN SCORE ELSE 0 END) 数学, MAX(CASE WHEN CNAME = 'ENGLISH' THEN SCORE ELSE 0 END) 英语 FROM SCORE_1 GROUP BY SNO;
2.pivot
语法:SELECT * FROM TB PIVOT(SUM(TB.COL1) FOR TB.COL2 IN (VAL1 AS NEW_COL1,VAL2 AS NEW_COL2,VAL3 AS NEW_COL3));
pivot必须含有聚合函数
SELECT * FROM SCORE_1 PIVOT(SUM(SCORE) FOR CNAME IN('CHINESE' AS 语文, 'MATH' AS 数学, 'ENGLISH' AS 英语));
四、SCORE_2==>SCORE_1
1.集合运算
SELECT SNO,'CHINESE' CNAME,语文 score FROM SCORE_2 union ALL SELECT SNO,'MATH' CNAME,数学 score FROM SCORE_2 union ALL SELECT SNO,'ENGLISH' CNAME,英语 score FROM SCORE_2;
2.unpivot
语法:SELECT * FROM TB UNPIVOT(NEW_COL1 FOR NEW_COL2 IN (TB.COL1 AS VAL1,TB.COL2 AS VAL2,TB.COL3 AS VAL3));
SELECT * FROM SCORE_2 UNPIVOT(SCORE FOR CNAME IN(语文 AS 'CHINESE', 数学 AS 'MATH', 英语 AS 'ENGLISH'));