QT5连接MySQL实现增删改查

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
using namespace std;
#include 
#include 
#include 
 
const char *kDbType = "QMYSQL";      // 数据库类型
const QString& kHost = "127.0.0.1";  // 数据库的ipd地址
const int kPort = 3306;              // 数据库端口号
const QString& kUsername = "root";   // 数据库账号
const QString& kPassword = "123456"; // 数据库密码
//const QString& dbname = "test";    // 数据库名
 
class DBSql{
 
private:
    QSqlDatabase db;    // 数据库操作对象
    QSqlQuery query;
    QSqlError error;    // SQLError对象
    bool flag;          // 判断函数是否执行
    bool DBInit(){
        db = QSqlDatabase::addDatabase(kDbType);
        db.setHostName(kHost);
        db.setPort(kPort);
        db.setUserName(kUsername);
        db.setPassword(kPassword);
        QString sqlname = "数据库连接";
        flag = db.open();
        sqlerror(flag,query,NULL,sqlname);
        return flag;
    }
    void sqlerror(bool flag,QSqlQuery query,QString sql,QString sqlname){
        if(flag){
            qDebug() << sqlname+"成功！" << sql;
        }else{
            error = query.lastError();
            qDebug() << sqlname+"失败！" << sql << error.driverText() << error.databaseText();
        }
    }
public:
 
    // 构造函数，初始化数据库连接
    DBSql(){
        this->DBInit();
    }
    // 设置数据库名
    void setDatabase(const QString& dbname){
        db.setDatabaseName(dbname);
        db.open();
    }
    // 查询表字段数
    int sqlRecord(const QString& sql){
        QSqlQuery query(sql);
        QSqlRecord record = query.record();
        int const n = record.count();
        qDebug()<<"查询的字段总数："<< n;
        return n;
    }
    // 查询结果总数
    int sqlTotal(const QString& sql){
        QSqlQuery query(sql);
        return query.size();
    }
    // 根据sql返回查询结果
    QString sqlQueryValue(const QString& sql){
        QSqlQuery query(db);
        flag = query.exec(sql);
        if(flag && query.next()){
            return query.value(0).toString();
        }else{
            sqlerror(false,query,sql,"返回查询结果失败");
            return NULL;
        }
    }
    // 增加记录
    bool sqlInsert(const QString& sql){
        QSqlQuery query(db);
        flag = query.exec(sql);
        sqlerror(flag,query,sql,"增加记录");
        return flag;
    }
    // 删除记录
    bool sqlDelete(const QString& sql){
        QSqlQuery query(db);
        flag = query.exec(sql);
        sqlerror(flag,query,sql,"删除记录");
        return flag;
    }
    // 查询记录
    list* sqlQuery1(const QString& sql){
        db.open();
        QSqlQuery query(db);
        query.exec(sql);
        const int count = query.record().count();
        const int total = query.size();
        cout<<"The number of fileds to query: "<* dot;
        int *in;
        dot = new list;
        int i = 0;
        while(query.next()){
            int j = 0;
            in = new int[4];
            while(jpush_back(in);
        sqlerror(flag,query,sql,"查询记录");
        return dot;
        }
    }
 
    int(*f(const QString& sql,const int total))[4]{
        db.open();
        QSqlQuery query(db);
        query.exec(sql);
        const int count = query.record().count();
        cout<<"The number of fileds to query: "<* li;
//    li = dbsql.sqlQuery1(sqlquery);
//    qDebug()<size();
//    list::iterator iterator;
//    for(iterator=li->begin();iterator!=li->end();++iterator){
//        cout<<*iterator<

/*
 Navicat Premium Data Transfer
 Source Server         : localhost_3306
 Source Server Type    : MySQL
 Source Server Version : 50556
 Source Host           : localhost:3306
 Source Schema         : test
 Target Server Type    : MySQL
 Target Server Version : 50556
 File Encoding         : 65001
 Date: 23/03/2020 12:09:27
*/
 
SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
 
-- ----------------------------
-- Table structure for xy
-- ----------------------------
DROP TABLE IF EXISTS `xy`;
CREATE TABLE `xy`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `x1` int(255) NULL DEFAULT NULL,
  `y1` int(255) NULL DEFAULT NULL,
  `x2` int(255) NULL DEFAULT NULL,
  `y2` int(255) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 10 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;
 
-- ----------------------------
-- Records of xy
-- ----------------------------
INSERT INTO `xy` VALUES (1, 1, 12, 3, 4);
INSERT INTO `xy` VALUES (2, 5, 6, 7, 8);
INSERT INTO `xy` VALUES (3, 9, 10, 11, 12);
INSERT INTO `xy` VALUES (7, 13, 14, 15, 16);
INSERT INTO `xy` VALUES (8, 17, 18, 19, 20);
INSERT INTO `xy` VALUES (9, 21, 22, 23, 24);
 
SET FOREIGN_KEY_CHECKS = 1;