创建sqlite数据库的过程---同mysql

 

 

 

 

 

 

 

 

建好sqlite数据库之后, 可以看到如下图所示:

 

 

 

 

参考网站: https://blog.csdn.net/wyansai/article/details/52901166

 

参考网站: https://www.cnblogs.com/xia-weiwen/archive/2017/05/04/6806709.html

 

在QT上建立一个控制台应用程序, 然后将代码直接复制上就可以编译测试.

还有就是需要在*.pro文件中添加: QT += sql

#include <QCoreApplication>

#include <QSqlDatabase>

#include <QSqlError>

#include <QSqlQuery>

#include <qDebug>

#include <QString>

int main(int argc, char *argv[])

{

QCoreApplication a(argc, argv);

bool success;

//建立数据库--加载数据库驱动

QSqlDatabase database;

if (QSqlDatabase::contains("qt_sql_default_connection"))

{

database = QSqlDatabase::database("qt_sql_default_connection");

}

else

{

database = QSqlDatabase::addDatabase("QSQLITE");

database.setDatabaseName("C:\\Users\\Administrator\\Desktop\\sqlite.db");

//db.setDatabaseName("main");//有这个会报错

//database.setUserName("");//可以省略

//database.setPassword("");//可以省略

}

//打开数据库if (!database.open())

{

qDebug() << "Error: Failed to connect database." << database.lastError();

return -1;

}

//#####################################################################

//--新建一个表student作为测试表

//#####################################################################

//执行sql语句---新建一个表

QSqlQuery sql_query;

/*QString create_sql = "create table student (id int, name varchar(30), age int)";

sql_query.prepare(create_sql);

success = sql_query.exec();

if(!success)

{

qDebug() << "Error: Fail to create table." << sql_query.lastError();

return -1;

}

else

{

qDebug() << "Table created!";

}*/

//#####################################################################

//--插入数据操作

//#####################################################################

//向student表中插入数据

//第一种方法:

/*success = sql_query.exec("insert into student values(1, 'xiaowen', 10)");

if(!success)

{

qDebug() << "Error: Fail to create table." << sql_query.lastError();

return -1;

}*/

//第二种方法:

QString sql = "insert into student values(3, 'xiaozi', 25)";

success = sql_query.exec(sql);

if(!success)

{

qDebug() << "Error: Fail to create table." << sql_query.lastError();

return -1;

}

//第三种方法:执行带有占位符的sql语句

QString insert_sql = "insert into student values (?, ?, ?)";

sql_query.prepare(insert_sql);

/*sql_query.addBindValue(2);

sql_query.addBindValue("xiaohu");

sql_query.addBindValue(22);*/

sql_query.bindValue(0, 5);

sql_query.bindValue(1, "小马");sql_query.bindValue(2, 30);

success = sql_query.exec();

if(!success)

{

qDebug() << sql_query.lastError();

return -1;

}

else

{

qDebug() << "inserted success!";

}

//批量插入

insert_sql = "insert into student values(?,?,?)";

sql_query.prepare(insert_sql);

QVariantList GroupIDs;

GroupIDs.append(0);

GroupIDs.append(1);

GroupIDs.append(2);

QVariantList GroupNames;

GroupNames.append("xiaoma");

GroupNames.append("xiaowei");

GroupNames.append("xiaolian");

QVariantList GroupAddress;

GroupAddress.append(10);

GroupAddress.append(15);

GroupAddress.append(18);

sql_query.addBindValue(GroupIDs);

sql_query.addBindValue(GroupNames);

sql_query.addBindValue(GroupAddress);

success = sql_query.execBatch();

if(!success)

{

qDebug()<<sql_query.lastError();

return -1;

}

else

{

qDebug()<<"insert batch data succ";

}

return 0;

//#####################################################################

//--更新数据

//#####################################################################

//QString update_sql = "update student set name = :name where id = :id";

QString update_sql = "update student set name = ? where id = ?";

sql_query.prepare(update_sql);

//sql_query.bindValue(":name", "Qt");//sql_query.bindValue(":id", 1);

sql_query.bindValue(0, "Qt");

sql_query.bindValue(1, 2);

success = sql_query.exec();

if(!success)

{

qDebug() << sql_query.lastError();

return -1;

}

else

{

qDebug() << "updated!";

}

//#####################################################################

//--查询数据

//#####################################################################

QString select_sql = "select id, name from student";

success = sql_query.exec();

if(!success)

{

qDebug()<<sql_query.lastError();

}

else

{

while(sql_query.next())

{

int id = sql_query.value(0).toInt();

QString name = sql_query.value(1).toString();

qDebug()<<QString("id:%1 name:%2").arg(id).arg(name);

}

}

//查询最大的ID

QString select_max_sql = "select max(id) from student";

int max_id = 0;

sql_query.prepare(select_max_sql);

success = sql_query.exec();

if(!success)

{

qDebug() << sql_query.lastError();

}

else

{

while(sql_query.next())

{

max_id = sql_query.value(0).toInt();

qDebug() << QString("max id:%1").arg(max_id);

}

}

//#####################################################################//--删除数据

//#####################################################################

QString delete_sql = "delete from student where id = ?";

sql_query.prepare(delete_sql);

sql_query.addBindValue(3);

success = sql_query.exec();

if(!success)

{

qDebug()<<sql_query.lastError();

return -1;

}

else

{

qDebug()<<"deleted!";

}

//清空表

/*QString clear_sql = "delete from student";

sql_query.prepare(clear_sql);

success = sql_query.exec();

if(!success)

{

qDebug() << sql_query.lastError();

return -1;

}

else

{

qDebug() << "table cleared";

}*/

//关闭数据库

database.close();

return a.exec();

}