数据库技术:golang通过mysql语句实现分页查询

1.前端接口调用

2.register访问入口

//查询一个用户下所有的subnet  ws.route(ws.get("/subnets").  to(sc.listsubnet).  doc("list subnets authorized to the login user.").  param(ws.queryparameter(query.parameterpage, "page").required(false).dataformat("page=%d").defaultvalue("page=1")).  param(ws.queryparameter(query.parameterlimit, "limit").required(false)).  returns(http.statusok, api.statusok, api.listresult{}))

3.解析参数

//查询某个用户下所有的subnet信息  func (v *subcontroller) listsubnet(request *restful.request, response *restful.response) {  username := request.attribute(filters.username).(string)    subnetservice := &service.subnetservice{}  query := query.parsequeryparameter(request)  result, err := subnetservice.listsubnet(query, v.db, username)  if err != nil {  api.handleerror(response, request, err)  return  }  response.writeentity(result)  }

4.service实现

//查询一个用户所有的subnet信息  func (ss *subnetservice) listsubnet(query *query.query, db *sql.db, username string) (*api.listresult, error) {  sm := mapper.newsubnetmapper(db)  sb, err := sm.searchallbyusername(query, username)  return sb, err  }

5.mapper实现

//查询用户下的所以信息  func (s *subnetmapper) searchallbyusername(query *query.query, username string) (*api.listresult, error) {    totalrow, err := s.db.query("select count(*) from t_subnet ,t_vpc where t_vpc.id = t_subnet.vpcid and username = ?", username)  if err != nil {  klog.error("query orders count error", err)  return nil, err  }  total := 0  for totalrow.next() {  err := totalrow.scan(  &total,  )  if err != nil {  klog.error("query orders count error", err)  continue  }  }  totalrow.close()    rows, err := s.db.query(searchallbyusernamesql, username, query.pagination.limit, query.pagination.offset)  defer func() {  if rows != nil {  rows.close()  }  }()  if err != nil {  klog.error("query subnet error", err)  return nil, err  }  items := make([]interface{}, 0)  for rows.next() {  ss := new(vpc.subnetitem)  err = rows.scan(&ss.vpcname, &ss.vpcnetwork, &ss.subnetname, &ss.subnetnetwork, &ss.createtime)  items = append(items, *ss)  }  return &api.listresult{  totalitems: total,  items: items,  }, nil  }  

可以看到第一步查出了所有count数目：

查询语句加上参数。控制查到的页数。

返回的是总数量跟当前查询页。

特殊情况用不到数据库分页的，就需要用到内存分页了，下期小编给大家讲解内存分页。