PostgreSQL递归查询

1. 语法结构

with recursive 名字 as (
    A.初始条件语句(非递归部分)
    
    union [all] 
    
    B.递归部分语句
) [SELECT | INSERT | UPDATE | DELETE]

1.1 说明

1. 前半部分A为初始条件语句，后半部分B为要进行的递归语句
2. 先执行A语句，然后将A语句的结果作为B语句的条件，如果需要对查询结果去重则使用union进行连接，否则使用union all进行连接

2 示例

2.1 表结构

DROP TABLE IF EXISTS "test"."rbac_menu";
CREATE TABLE "test"."rbac_menu" (
  "id" int8 NOT NULL,
  "pid" int8,
  "menu_name" varchar(255) COLLATE "pg_catalog"."default"
)
;
COMMENT ON COLUMN "test"."rbac_menu"."id" IS 'ID';
COMMENT ON COLUMN "test"."rbac_menu"."pid" IS '父ID';
COMMENT ON COLUMN "test"."rbac_menu"."menu_name" IS '菜单名称';

-- ----------------------------
-- Records of rbac_menu
-- ----------------------------
INSERT INTO "test"."rbac_menu" VALUES (100101, 1001, '权限管理');
INSERT INTO "test"."rbac_menu" VALUES (10010101, 100101, '菜单管理');
INSERT INTO "test"."rbac_menu" VALUES (10010102, 100101, '用户管理');
INSERT INTO "test"."rbac_menu" VALUES (10010103, 100101, '角色管理');
INSERT INTO "test"."rbac_menu" VALUES (1001010101, 10010101, '设置角色');
INSERT INTO "test"."rbac_menu" VALUES (1001010102, 10010101, '设置用户');
INSERT INTO "test"."rbac_menu" VALUES (1001010301, 10010103, '查看');
INSERT INTO "test"."rbac_menu" VALUES (1001010302, 10010103, '新增');
INSERT INTO "test"."rbac_menu" VALUES (1001010303, 10010103, '修改');
INSERT INTO "test"."rbac_menu" VALUES (1001010304, 10010103, '删除');

-- ----------------------------
-- Primary Key structure for table rbac_menu        
-- ----------------------------
ALTER TABLE "test"."rbac_menu" ADD CONSTRAINT "rbac_menu_pkey" PRIMARY KEY ("id");

2.1 根据父节点获取所有子节点信息

with recursive temp_table as (
    select "id", pid, "menu_name" from rbac_menu where pid = 1001
    union
        select a."id", a.pid, a."menu_name" from rbac_menu a,temp_table b where a.pid = b."id"
) select * from temp_table
order by pid, "id";

2.2 根据子节点获取所有父节点信息

with recursive temp_table as (
    select "id", pid, "menu_name" from rbac_menu where "id" = 10060101
    union
        select a."id", a.pid, a."menu_name" from rbac_menu a,temp_table b where a.id = b.pid
) select * from temp_table
order by pid desc, "id" desc