image.png

2表查询

image.png

  1. const user_Schema = require("../model/user_Schema");//(第1个表)
  2. const role_Schema = require("../model/role_Schema");//(第2个表)
  3. const user_role_Schema = require("../model/t_user_role_Schema");
  5. router.get('/',async(req,res)=>{
  6.   let result=await user_Schema.aggregate([
  7.     {
  8.       $lookup:
  9.       {
  10.         from: "role", //关联第二张表(角色)
  11.         localField: "pid",//user表的主键id  (第1个表)
  12.         foreignField: "id_name_",  //role角色 表 主键ID的字段  (第2个表role)
  13.         as: "items"
  14.       }
  15.     }
  16.   ])
  17.   console.log(result);
  18.   res.send(result)
  19. })

image.png

3表查询

  1. router.get('/',async(req,res)=>{
  3.   let result=await user_Schema.aggregate([
  4.     {
  5.       lookup:
  6.       {
  7.         from: "t_user_role", //关联第二张表(角色)
  8.         localField: "pidxxx",//user表的主键id  (第1个表)
  9.         foreignField: "id_namexxxx_",  //role角色 表 主键ID的字段  (第2个表role)
  10.         as: "items"
  11.       }
  12.     }
  13.   ])
  14.   console.log(result);
  15.   res.send(result)
  16. })
  17. module.exports=router;

4表查询之条件

  1. router.get('/',async(req,res)=>{
  3.   let result=await user_Schema.aggregate([
  4.     {
  5.       match:{id_name:1}
  6.     }
  7.   ])
  8.   console.log(result);
  9.   res.send(result)
  10. })
  11. module.exports=router;
  1. [{"id":"60b0bc4c74d0832de80b8db2","id_name":1,"username":"陈陈","pid":1,"uid":1,"items":[{"id":"60b0a41e898fd52f8c99dc75","role_name":"管理员","id_name_":1}]}]