c++ - 我的 SQL 查询被中断

Question

我有这门课:

#include <QSqlError>
#include <QMessageBox>
#include <QCompleter>
#include <QFile>
#include <QTextStream>
#include <QSqlQueryModel>

#include "items.h"

Items::Items(Ui::Store *setui)
{
    form = setui;
}

void Items::getItem(int index, QString item)
{
    if(index == 1)
    {
        sqlQuery = "SELECT * FROM Items WHERE Name='" + item + "'";
        query.exec(sqlQuery);
        query.next();
        rec = query.record();

        form->itemNumManMod->setText(query.value(rec.indexOf("ID_I")).toString());
        form->purchaseManMod->setText(query.value(rec.indexOf("Purchase")).toString());
        form->saleManMod->setText(query.value(rec.indexOf("Sale")).toString());
        form->countityManMod->setText(query.value(rec.indexOf("Countity")).toString());
        form->totaleManMod->setText(query.value(rec.indexOf("Totale")).toString());
        form->minimumManMod->setText(query.value(rec.indexOf("Minimum")).toString());
        form->restManMod->setText(query.value(rec.indexOf("Rest")).toString());
        form->wsPriceManMod->setText(query.value(rec.indexOf("Vendor")).toString());
        form->wsNumManMod->setText(query.value(rec.indexOf("Min")).toString());
        QString x = idToCategory(3);
        QMessageBox::critical(0, "dd", x);
    }
    else if(index == 2)
    {
        sqlQuery = "SELECT * FROM Items WHERE Name='" + item + "'";
        query.exec(sqlQuery);
        query.next();
        rec = query.record();

        form->itemNumManDel->setText(query.value(rec.indexOf("ID_I")).toString());
        form->itemNameManDel->setText(query.value(rec.indexOf("Name")).toString());
        form->purchaseManDel->setText(query.value(rec.indexOf("Purchase")).toString());
        form->saleManDel->setText(query.value(rec.indexOf("Sale")).toString());
        form->countityManDel->setText(query.value(rec.indexOf("Countity")).toString());
        form->totaleManDel->setText(query.value(rec.indexOf("Totale")).toString());
        form->minimumManDel->setText(query.value(rec.indexOf("Minimum")).toString());
        form->restManDel->setText(query.value(rec.indexOf("Rest")).toString());
    }
    else if(index == 0)
    {
        sqlQuery = "SELECT ID_I, Sale FROM Items WHERE Name='" + item + "'";
        query.exec(sqlQuery);
        query.next();
        rec = query.record();
        form->numSaleAdd->setText(query.value(rec.indexOf("ID_I")).toString());
        form->priceSaleAdd->setText(query.value(rec.indexOf("Sale")).toString());
    }
}

QString Items::idToCategory(int id)
{
    sqlQuery = "SELECT Name FROM Category WHERE ID_C=" + id;
    query.exec(sqlQuery);
    query.next();
    rec = query.record();
    QString name = query.value(rec.indexOf("Name")).toString();
    return query.lastQuery();
}

当我调用 idToCategory() 方法时，它返回:

ECT Name FROM Items WHERE ID_C=

但是它应该返回这样的东西:

SELECT Name FROM Items WHERE ID_C=3

Answer 1

 sqlQuery = "SELECT Name FROM Category WHERE ID_C=" + id;

您正在向指针添加一个整数值。试试这个:

sqlQuery = QString("SELECT Name FROM Category WHERE ID_C=%1").arg(id);

或者更好的是，使用准备好的语句，并绑定(bind)值:

sqlQuery = "SELECT Name FROM Category WHERE ID_C = :id";
query.prepare(sqlQuery);
query.bindValue(":id", id);
query.exec(); // note that you should be testing the return value of exec()

PS:对于您的其他查询，您应该查看带有QSqlTableModel 的QDataWidgetMapper，以便一次性将所有字段值映射到每个小部件，而不是重新分配手动值。