//准备执行的sql语句，此为带参的sql语句
        query.prepare("update employee set Name=:Name, Gender=:Gender,Height=:Height,"
                      " Birthday=:Birthday, Mobile=:Mobile, Province=:Province,"
                      " City=:City, Department=:Department, Education=:Education,"
                      " Salary=:Salary, Memo=:Memo, Photo=:Photo "
                      " where EmpNo = :ID");
        
        //设置sql语句中参数的值
        query.bindValue(":Name",recData.value("Name"));
        query.bindValue(":Gender",recData.value("Gender"));
        query.bindValue(":Height",recData.value("Height"));
        query.bindValue(":Birthday",recData.value("Birthday"));
        query.bindValue(":Mobile",recData.value("Mobile"));

        query.bindValue(":Province",recData.value("Province"));
        query.bindValue(":City",recData.value("City"));
        query.bindValue(":Department",recData.value("Department"));
        query.bindValue(":Education",recData.value("Education"));

        query.bindValue(":Salary",recData.value("Salary"));
        query.bindValue(":Memo",recData.value("Memo"));
        query.bindValue(":Photo",recData.value("Photo"));

        query.bindValue(":ID",empNo);
        //执行对应绑定值的sql语句
        if (!query.exec())
            QMessageBox::critical(this, "错误", "记录更新错误\n"+query.lastError().text(),
                                     QMessageBox::Ok,QMessageBox::NoButton);

删除：

QSqlQuery query;
    query.prepare("delete  from employee where EmpNo = :ID");
    query.bindValue(":ID",empNo);

    if (!query.exec())
        QMessageBox::critical(this, "错误", "删除记录出现错误\n"+query.lastError().text(),
                                 QMessageBox::Ok,QMessageBox::NoButton);

修改：

QSqlQuery qryUpdate; //临时 QSqlQuery
    qryUpdate.prepare("UPDATE employee SET Salary=:Salary WHERE EmpNo = :ID");
 qryUpdate.bindValue(":ID",empID);
        qryUpdate.bindValue(":Salary",salary); //设置SQL语句参数
        qryUpdate.exec(); //执行update

插入：

query.prepare("INSERT INTO employee (EmpNo,Name,Gender,Height,Birthday,Mobile,Province,"
                      " City,Department,Education,Salary,Memo,Photo) "
                      " VALUES(:EmpNo,:Name, :Gender,:Height,:Birthday,:Mobile,:Province,"
                      " :City,:Department,:Education,:Salary,:Memo,:Photo)");

        query.bindValue(":EmpNo",recData.value("EmpNo"));
        query.bindValue(":Name",recData.value("Name"));
        query.bindValue(":Gender",recData.value("Gender"));
        query.bindValue(":Height",recData.value("Height"));
        query.bindValue(":Birthday",recData.value("Birthday"));
        query.bindValue(":Mobile",recData.value("Mobile"));

        query.bindValue(":Province",recData.value("Province"));
        query.bindValue(":City",recData.value("City"));
        query.bindValue(":Department",recData.value("Department"));
        query.bindValue(":Education",recData.value("Education"));

        query.bindValue(":Salary",recData.value("Salary"));
        query.bindValue(":Memo",recData.value("Memo"));
        query.bindValue(":Photo",recData.value("Photo"));

        if (!query.exec())
            QMessageBox::critical(this, "错误", "插入记录错误\n"+query.lastError().text(),
                                     QMessageBox::Ok,QMessageBox::NoButton);