Qt SQL模塊是Qt中用來(lái)操作數(shù)據(jù)庫(kù)的類，該類封裝了各種SQL數(shù)據(jù)庫(kù)接口，可以很方便的鏈接并使用，數(shù)據(jù)的獲取也使用了典型的Model/View結(jié)構(gòu)，通過(guò)MV結(jié)構(gòu)映射我們可以實(shí)現(xiàn)數(shù)據(jù)與通用組件的靈活綁定，一般SQL組件常用的操作，包括，讀取數(shù)據(jù)，插入數(shù)據(jù)，更新數(shù)據(jù)，刪除數(shù)據(jù)，這四個(gè)功能我將分別介紹它是如何使用的。

SQL模塊在使用時(shí)必須引入模塊，需要在pro文件內(nèi)增加QT += sql并在頭文件內(nèi)增加#include <QSqlDatabase>導(dǎo)入模塊才可以正常使用。

初始化數(shù)據(jù)庫(kù): 初始化調(diào)用QSqlDatabase::addDatabase指定數(shù)據(jù)庫(kù)類型,通過(guò)db.setDatabaseName()指定數(shù)據(jù)庫(kù)文件名.

#include <QCoreApplication>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>
#include <QSqlRecord>
#include <iostream>
#include <QStringList>
#include <QString>
#include <QVariant>

// 初始化表結(jié)構(gòu)
// https://www.cnblogs.com/lyshark
bool InitSQL()
{
  // 指定數(shù)據(jù)庫(kù)驅(qū)動(dòng)類型
  QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
  db.setDatabaseName("./lyshark.db");
   if (!db.open())
   {
          std::cout << db.lastError().text().toStdString()<< std::endl;
          return false;
   }

  // 執(zhí)行SQL創(chuàng)建表
  db.exec("DROP TABLE LyShark");
  db.exec("CREATE TABLE LyShark ("
                  "id INTEGER PRIMARY KEY AUTOINCREMENT, "
                  "name VARCHAR(40) NOT NULL, "
                  "age INTEGER NOT NULL)"
       );

  // 提交事務(wù)請(qǐng)求
  bool ref = db.commit();
  db.close();
  return ref;
}

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  bool ref = InitSQL();
  std::cout << "init: " << ref << std::endl;

  return a.exec();

初始化表結(jié)構(gòu)如下:

逐條插入數(shù)據(jù):逐條插入記錄在Qt中可直接調(diào)用SQL模塊提供的db.exec()函數(shù),插入后最后需要調(diào)用db.commit()一次性提交事務(wù).

#include <QCoreApplication>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>
#include <QSqlRecord>
#include <iostream>
#include <QStringList>
#include <QString>
#include <QVariant>

// 逐條插入數(shù)據(jù)
// https://www.cnblogs.com/lyshark
bool InsertSQL()
{
  QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
  db.setDatabaseName("./lyshark.db");
   if (!db.open())
   {
          std::cout << db.lastError().text().toStdString()<< std::endl;
          return false;
   }

   // 逐條插入數(shù)據(jù)
   db.exec("INSERT INTO LyShark(name,age) ""VALUES ('admin',23)");
   db.exec("INSERT INTO LyShark(name,age) ""VALUES ('zhangsan',25)");
   db.exec("INSERT INTO LyShark(name,age) ""VALUES ('lisi',34)");

   // 提交數(shù)據(jù)
   bool ref = db.commit();
   return ref;
}

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  bool ref = InsertSQL();
  std::cout << "insert = > " << ref << std::endl;

  return a.exec();
}

插入記錄如下:

多條記錄插入:一次性插入多條數(shù)據(jù)記錄,可調(diào)用query.prepare()綁定字段與SQL記錄,綁定后即可通過(guò)循環(huán)批量插入記錄.

#include <QCoreApplication>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>
#include <QSqlRecord>
#include <iostream>
#include <QStringList>
#include <QString>
#include <QVariant>

// 批量插入數(shù)據(jù)
// https://www.cnblogs.com/lyshark
bool InsertMultipleSQL()
{
  QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
  db.setDatabaseName("./lyshark.db");
  if (!db.open())
  {
         std::cout << db.lastError().text().toStdString()<< std::endl;
         return false;
  }

  // 定義字符串鏈表
  QStringList user_name;
  QStringList user_age;

  // 批量插入數(shù)據(jù)到鏈表中
  user_name << "www.lyshark.com" << "https://www.cnblogs.com/lyshark" << "lyshark";
  user_age << "22" << "33" << "44";

  // 綁定數(shù)據(jù)記錄
  QSqlQuery query;
  query.prepare("INSERT INTO LyShark(name,age) ""VALUES (:name, :age)");

  // 判斷兩張表中字段數(shù)據(jù)量是否一致
  if(user_name.size() == user_age.size())
  {
      // 循環(huán)插入數(shù)據(jù)
      for(int x=0;x< user_name.size(); x++)
      {
          query.bindValue(":name",user_name[x]);
          query.bindValue(":age",user_age[x]);
          query.exec();
      }
  }
  // 提交數(shù)據(jù)
  db.commit();
}

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  bool ref = InsertMultipleSQL();
  std::cout << "insert = > " << ref << std::endl;

  return a.exec();
}

批量插入數(shù)據(jù)如下:

查詢表中記錄: 查詢記錄可調(diào)用QSqlQuery query()得到記錄條數(shù),然后不斷循環(huán),每次循環(huán)調(diào)用一次query.next()獲取一條,直到循環(huán)結(jié)束.

#include <QCoreApplication>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>
#include <QSqlRecord>
#include <iostream>
#include <QStringList>
#include <QString>
#include <QVariant>

// 查詢數(shù)據(jù)記錄
// https://www.cnblogs.com/lyshark
bool SelectSQL()
{
  QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
  db.setDatabaseName("./lyshark.db");
   if (!db.open())
   {
          std::cout << db.lastError().text().toStdString()<< std::endl;
          return false;
   }

   // 查詢數(shù)據(jù)
   QSqlQuery query("SELECT * FROM LyShark;",db);
   QSqlRecord rec = query.record();

   // 循環(huán)所有記錄
   while(query.next())
   {
       // 判斷當(dāng)前記錄是否有效
       if(query.isValid())
       {
           int id_ptr = rec.indexOf("id");
           int id_value = query.value(id_ptr).toInt();

           int name_ptr = rec.indexOf("name");
           QString name_value = query.value(name_ptr).toString();

           int age_ptr = rec.indexOf("age");
           int age_value = query.value(age_ptr).toInt();

           std::cout << "ID: " << id_value << "Name: " << name_value.toStdString() << "Age: " << age_value << std::endl;
       }
   }
   return true;
}

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  bool ref = SelectSQL();
  std::cout << "select = > " << ref << std::endl;

  return a.exec();
}

循環(huán)輸出的數(shù)據(jù)如下:

更新表中記錄: 更新表中記錄直接調(diào)用update語(yǔ)句即可,在調(diào)用之前通過(guò)QString sql拼接待修改語(yǔ)句并提交db.commit()事務(wù)即可完成更新.

#include <QCoreApplication>
#include <QSqlDatabase>
#include <QSqlError>
#include <QSqlQuery>
#include <QSqlRecord>
#include <iostream>
#include <QStringList>
#include <QString>
#include <QVariant>

// 修改表中數(shù)據(jù)
// https://www.cnblogs.com/lyshark
bool UpdateSQL(QString uid, QString new_name)
{
  // 指定數(shù)據(jù)庫(kù)驅(qū)動(dòng)類型
  QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
  db.setDatabaseName("./lyshark.db");
   if (!db.open())
   {
          std::cout << db.lastError().text().toStdString()<< std::endl;
          return false;
   }

  // 執(zhí)行SQL更新記錄
  QString sql = QString("update LyShark set name='%1' where id=%2;").arg(new_name).arg(uid);
  db.exec(sql);
  std::cout << "update => " << sql.toStdString() << std::endl;

  // 提交事務(wù)請(qǐng)求
  bool ref = db.commit();
  db.close();
  return true;
}

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  // 更新ID=6的記錄更新為 www.cnblogs.com/lyshark
  bool ref = UpdateSQL("6","www.cnblogs.com/lyshark");
  std::cout << "update flag: " << ref << std::endl;

  return a.exec();
}

到此這篇關(guān)于C/C++ Qt 數(shù)據(jù)庫(kù)QSql增刪改查組件應(yīng)用教程的文章就介紹到這了,更多相關(guān)C++ Qt 數(shù)據(jù)庫(kù)QSql增刪改查內(nèi)容請(qǐng)搜索服務(wù)器之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持服務(wù)器之家！

原文鏈接：https://www.cnblogs.com/LyShark/p/15649713.html