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，下期给大家讲解内存分页。

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