listagg()行转列函数[通俗易懂]

--基础数据
DROP TABLE "ZYH_TEST";
CREATE TABLE "ZYH_TEST" (
"ID" NUMBER(19) NOT NULL ,
"NAME" VARCHAR2(255 BYTE) ,
"CREATETIME" DATE ,
"SCORE" NUMBER ,
"CLASSID" VARCHAR2(255 BYTE) 
)
INSERT INTO "ZYH_TEST" VALUES ('1', 'allen', TO_DATE('2019-01-14 17:41:09', 'SYYYY-MM-DD HH24:MI:SS'), '98.5', '1');
INSERT INTO "ZYH_TEST" VALUES ('2', 'lee', TO_DATE('2019-01-14 17:41:37', 'SYYYY-MM-DD HH24:MI:SS'), '88.5', '1');
INSERT INTO "ZYH_TEST" VALUES ('3', 'me', TO_DATE('2019-01-14 17:41:52', 'SYYYY-MM-DD HH24:MI:SS'), '73', '1');
INSERT INTO "ZYH_TEST" VALUES ('4', 'let', TO_DATE('2019-01-14 17:42:03', 'SYYYY-MM-DD HH24:MI:SS'), '88', '1');
INSERT INTO "ZYH_TEST" VALUES ('5', 'met', TO_DATE('2019-01-14 17:42:16', 'SYYYY-MM-DD HH24:MI:SS'), '99', '1');
INSERT INTO "ZYH_TEST" VALUES ('6', 'ali', TO_DATE('2019-01-14 17:42:30', 'SYYYY-MM-DD HH24:MI:SS'), '66', '1');
INSERT INTO "ZYH_TEST" VALUES ('7', 'avicii', TO_DATE('2019-01-15 12:41:09', 'SYYYY-MM-DD HH24:MI:SS'), '73', '2');
INSERT INTO "ZYH_TEST" VALUES ('8', 'martin', TO_DATE('2019-01-15 12:41:37', 'SYYYY-MM-DD HH24:MI:SS'), '76', '2');
INSERT INTO "ZYH_TEST" VALUES ('9', 'ajx', TO_DATE('2019-01-15 12:41:52', 'SYYYY-MM-DD HH24:MI:SS'), '91', '2');
INSERT INTO "ZYH_TEST" VALUES ('10', 'atlan', TO_DATE('2019-01-15 12:42:03', 'SYYYY-MM-DD HH24:MI:SS'), '60', '3');
INSERT INTO "ZYH_TEST" VALUES ('11', 'bill', TO_DATE('2019-01-15 12:42:16', 'SYYYY-MM-DD HH24:MI:SS'), '78', '3');
INSERT INTO "ZYH_TEST" VALUES ('12', 'bite', TO_DATE('2019-01-15 12:42:30', 'SYYYY-MM-DD HH24:MI:SS'), '89', '3');

--listagg()函数：是行转列函数，用于实现对列值的拼接（多行中的指定列字段，拼接成新的一列）。
--格式
listagg(列字段,'分隔符')within group(order by 排序字段)

--分数大于70的学生
select listagg(name,',')within group(order by score) 合并后的姓名 from zyh_test  WHERE score > 70;
--每个班级分数大于70的学生
select classid 班级,listagg(name,',')within group(order by score) 合并后的姓名 from zyh_test  WHERE score > 70 GROUP BY classid;

--列转行函数listagg（）结合分析函数over（）
select name 姓名,score 分数,classid 班级,listagg(name,',')within group(order by score) over (partition by classid) 合并后的姓名 from zyh_test ORDER BY classid,score;