如何利用golang运用mysql数据库

import (     "database/sql"     "fmt"     _ "github.com/go-sql-driver/mysql" )

package main import (     _ "container_cloud/pkg/config"     "container_cloud/pkg/utils/httputil"     "container_cloud/routers"     "database/sql"     "fmt"     _ "github.com/go-sql-driver/mysql"     "net/http"     "time" ) func init() {     httputil.InitHttpTool() } // mysql const (     USERNAME = "root"     PASSWORD = "Admin123"     NETWORK  = "tcp"     // TODO  本地调试时放开     /*SERVER   = "192.168.103.48"     PORT     = 43306*/     // TODO 部署到环境时放开     SERVER   = "192.168.66.4"     PORT     = 3306     DATABASE = "container_cloud" ) func main() {     var err error     dsn := fmt.Sprintf("%s:%s@%s(%s:%d)/%s?parseTime=1&multiStatements=1&charset=utf8mb4&collation=utf8mb4_unicode_ci", USERNAME, PASSWORD, NETWORK, SERVER, PORT, DATABASE)     db, err := sql.Open("mysql", dsn)     if err != nil {         fmt.Printf("Open mysql failed,err:%v\n", err)         return     }     //最大连接周期，超过时间的连接就close     db.SetConnMaxLifetime(100 * time.Second)     //设置最大连接数     db.SetMaxOpenConns(100)     //设置闲置连接数     db.SetMaxIdleConns(16)     defer db.Close()     container := routers.InitApiRouter(db)     server := &http.Server{Addr: ":8090", Handler: container}     server.ListenAndServe() }

package v1alpha1 import (     "container_cloud/pkg/api"     "container_cloud/pkg/apiserver/query"     "container_cloud/pkg/apiserver/runtime"     "container_cloud/pkg/controller"     "container_cloud/pkg/domain"     "database/sql"     "github.com/emicklei/go-restful"     "k8s.io/apimachinery/pkg/runtime/schema"     "net/http" ) const (     GroupName = "order.ictnj.io"     Version   = "v1alpha1" ) var GroupVersion = schema.GroupVersion{Group: GroupName, Version: Version} func AddToContainer(db *sql.DB) *restful.WebService{     ws := runtime.NewWebService(GroupVersion)     orderController := controller.NewOrderController(db)     // 创建订单接口，pvc创建、负载创建的时候，是在特定命名空间下。（其实请求入参中也有命名空间字段，资源创建的时候也可以从入参中获取）     ws.Route(ws.POST("/namespaces/{namespace}/orders").         To(orderController.CreateOrder).         Param(ws.PathParameter("namespace", "namespace name")).         Returns(http.StatusOK, api.StatusOK, map[string]string{}).         Doc("create order."))     return ws } 

type orderController struct {     Db *sql.DB } func NewOrderController(db *sql.DB) *orderController{     return &orderController{Db: db} } // 再创建订单     orderService := service.NewOrderService(o.Db)     orderService.CreateOrder(order)     result := map[string]string{"message": "success"}     response.WriteEntity(result)

package service import (     "container_cloud/pkg/api"     "container_cloud/pkg/apiserver/query"     "container_cloud/pkg/domain"     "database/sql"     "encoding/json"     "fmt"     "github.com/google/uuid"     "k8s.io/klog"     "strings"     "time" ) type OrderService struct {     Db *sql.DB } func NewOrderService(db *sql.DB) *OrderService{     return &OrderService{Db: db} } func (o *OrderService) CreateOrder(order domain.Order) {     order.CreateTime = time.Now()     var orderType uint8 = 1     order.OrderType = &orderType     uuid,_ := uuid.NewRandom()     order.Id = strings.ReplaceAll(uuid.String(), "-", "")     jsonbyte, _ := json.Marshal(order.OrderItem)     order.OrderItemJson = string(jsonbyte)     o.insertData(order) } func (o *OrderService) insertData(order domain.Order) {     stmt, _ := o.Db.Prepare(`INSERT INTO t_order (id, username, service_type, order_type, status, reason, order_item, create_time) VALUES (?, ?, ?, ?, ?, ?, ?, ?)`)     defer stmt.Close()     ret, err := stmt.Exec(order.Id, order.Username, order.ServiceType, order.OrderType, order.Status, order.Reason, order.OrderItemJson, order.CreateTime)     if err != nil {         fmt.Printf("insert data error: %v\n", err)         return     }     if LastInsertId, err := ret.LastInsertId(); nil == err {         fmt.Println("LastInsertId:", LastInsertId)     }     if RowsAffected, err := ret.RowsAffected(); nil == err {         fmt.Println("RowsAffected:", RowsAffected)     } } func (o *OrderService) ListOrders(query *query.Query, username string) (*api.ListResult, error){     // 查询总数量     totalRow, err := o.Db.Query("SELECT COUNT(*) FROM t_order WHERE 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()     // 查询订单列表     rows, err := o.Db.Query("select * from t_order where username = ? order by create_time desc limit ? offset ? ", username, query.Pagination.Limit, query.Pagination.Offset)     defer func() {         if rows != nil {             rows.Close()         }     }()     if err != nil {         klog.Error("query orders error", err)         return nil, err     }     items := make([]interface{}, 0)     for rows.Next() {         order := new(domain.Order)         err = rows.Scan(&order.Id, &order.Username, &order.ServiceType, &order.OrderType, &order.Status, &order.Reason, &order.OrderItemJson, &order.CreateTime)         if err != nil {             klog.Error("query orders error", err)             return nil, err         }         order.OrderItemJson = ""         items = append(items, *order)     }     return &api.ListResult{         TotalItems: total,         Items:      items,     }, nil } func (o *OrderService) GetOrder(id string) (*domain.Order, error) {     order := new(domain.Order)     row := o.Db.QueryRow("select order_item from t_order where id = ?", id)     if err := row.Scan(&order.OrderItemJson); err != nil {         klog.Error(err)         return nil, err     }     orderItems := &[]domain.OrderItem{}     json.Unmarshal([]byte(order.OrderItemJson), orderItems)     order.OrderItemJson = ""     order.OrderItem = *orderItems     return order, nil } func (o *OrderService) ListUserOrders(username string) (*[]domain.Order, error){     // 查询订单列表     rows, err := o.Db.Query("select * from t_order where username = ? order by create_time desc", username)     defer func() {         if rows != nil {             rows.Close()         }     }()     if err != nil {         klog.Error("query orders error", err)         return nil, err     }     items :=  make([]domain.Order,0)     for rows.Next() {         order := new(domain.Order)         err = rows.Scan(&order.Id, &order.Username, &order.ServiceType, &order.OrderType, &order.Status, &order.Reason, &order.OrderItemJson, &order.CreateTime)         if err != nil {             klog.Error("query orders error", err)             return nil, err         }         order.OrderItemJson = ""         items = append(items, *order)     }     return &items,nil }