postgresql 数据库 查询集合结果如何用逗号分隔返回字符串处理的操作
关键字：
string_agg(” , ”)
例如：
select string_agg(name||” , ‘,’) from sys_user
补充：PostgreSQL 字段用逗号 “，”隔开 判断是否含有某个值
Array Functions and Operators
https://www.postgresql.org/docs/9.2/functions-array.html
— —————————-
— Table structure for T_STUDENT
— —————————-
DROP TABLE IF EXISTS “public”.”T_STUDENT”;
CREATE TABLE “public”.”T_STUDENT” (
“id” int4,
“name” varchar(255) COLLATE “default”,
“course” varchar(255) COLLATE “default”
)
WITH (OIDS=FALSE)
;
— —————————-
— Records of T_STUDENT
— —————————-
INSERT INTO “public”.”T_STUDENT” VALUES (‘1’, ‘李四’, ‘12,45,1,66,7,89’);
INSERT INTO “public”.”T_STUDENT” VALUES (‘2’, ‘刘一’, ‘1,5,8,9’);
INSERT INTO “public”.”T_STUDENT” VALUES (‘3’, ‘王五’, ‘0,4,2’);
INSERT INTO “public”.”T_STUDENT” VALUES (‘4’, ‘张三’, ‘1,2,5,7’);
— —————————-
— Alter Sequences Owned By
— —————————-
— —————————-
— Table structure for T_STUDENT
— —————————-
DROP TABLE IF EXISTS “public”.”T_STUDENT”;
CREATE TABLE “public”.”T_STUDENT” (
“id” int4,
“name” varchar(255) COLLATE “default”,
“course” varchar(255) COLLATE “default”
)
WITH (OIDS=FALSE)
;
— —————————-
— Records of T_STUDENT
— —————————-
INSERT INTO “public”.”T_STUDENT” VALUES (‘1’, ‘李四’, ‘12,45,1,66,7,89’);
INSERT INTO “public”.”T_STUDENT” VALUES (‘2’, ‘刘一’, ‘1,5,8,9’);
INSERT INTO “public”.”T_STUDENT” VALUES (‘3’, ‘王五’, ‘0,4,2’);
INSERT INTO “public”.”T_STUDENT” VALUES (‘4’, ‘张三’, ‘1,2,5,7’);
— —————————-
— Alter Sequences Owned By
— —————————-
id name course
4 张三 1,2,5,7
1 李四 12,45,1,5,66,7,89
2 刘一 1,5,8,9
3 王五 0,4,2
SELECT * FROM “public”.”T_STUDENT” WHERE string_to_array(course, ‘,’) @> ARRAY[‘2′,’7’]
结果：
id name course
4 张三 1,2,5,7
SELECT * FROM “public”.”T_STUDENT” WHERE string_to_array(course, ‘,’) <@ array[‘5′,’12’,’45’,’1′,’0′,’4′,’2′]
结果：
id name course
3 王五 0,4,2
SELECT * FROM “public”.”T_STUDENT” WHERE string_to_array(course, ‘,’) && ARRAY[‘5′,’8′,’225′,’111’]
结果：
id name course
4 张三 1,2,5,7
2 刘一 1,5,8,9
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。如有错误或未考虑完全的地方，望不吝赐教。
