How to connect mysql with qt

How to connect mysql and qt: first download and install mysql and qt; then enter SQL related instructions in the "cmd.exe" software; then create the QT program; finally add in the "sql_test.pro" file "QT =sql" is enough.

Recommendation: "mysql video tutorial"

Because QT is needed to read the data in the database , and save the data to the database. It took a day to finally realize reading the data in the database from QT. There is a lot of relevant information on the Internet, but it is not comprehensive. Some problems arise in the middle, which are troublesome to solve. Therefore, this article downloads and installs from MYSQL and connects QT to MYSQL in as much detail as possible. If there are any shortcomings, please forgive me.

1. QT5.5 download

The windows32 QT5.5 version used in this article is (qt-opensource-windows-x86-mingw492-5.5.10), which can be downloaded from my Baidu Cloud: https://pan.baidu.com/s/1XsVmgd3Qd-J0BHPVOtMVkA download

If you choose a higher version, you can refer to Baidu for the specific installation method.

2. MYSQL5.6 download

Since QT uses Windows 32-bit, MYSQL should also choose the Windows 32-bit version as mysql-5.6.39-win32.zip. (If QT selects Windows 64-bit, MYSQL should select Windows 64-bit),

can be downloaded from my Baidu Cloud: https://pan.baidu.com/s/1XsVmgd3Qd-J0BHPVOtMVkA.

If you choose a higher version, you can refer to Baidu for the specific download method.

3. MYSQL5.6 installation

1) Extract mysql-5.6.39-win32.zip to MYSQL SERVER in the D drive, and rename it to mysql-5.6. The result after decompression and modification is shown in Figure 1-1.

# 图 1-1

## 2) Modify my-default.ini, after modification, as shown in Figure 1-2

##                                                                                                                                                                                                                . Right-click My Computer, click Properties, click Advanced System Settings, click Environment Variables, and add

;D:\MYSQL SERVER\mysql-5.6\bin to PATH (don’t forget the semicolon, according to your own installation Directory rewriting), click OK.

4) Find cmd.exe in the C drive and open it with administrator rights. Execute the following instructions respectively:

d: cd MYSQL SERVER\mysql-5.6\bin

mysqld -initalize -user=mysql -console

mysqld -install, after entering this command, it will print Service successfully installed

net start mysql, after entering this command, it will print that the MySQL service has been started successfully. At this point, MYSQL5.6 has been installed successfully and is running.

4. MYSQL login and password change

1) In the cmd.exe software, continue to enter SQL related commands:

mysql -u root -p, Enter password: appears after entering this command, press Enter directly when logging in for the first time, and enter the mysql software. As shown in Figure 1-3

                                                                                                    # 2) Add root password. mysql> set password for root@localhost=password('88888888');

After entering this command, the password of ront becomes 88888888. (When writing QT programs, the user name is root and the password is 88888888)

mysql>exit

Enter this command and exit.

Log in again, enter mysql -u root -p, Enter password: will appear after entering this command, enter 88888888. If the entered password is not 88888888, an error will appear, as shown in Figure 1-4 ## 3) Add a test table in Add the student table to the test library and add some data. The specific operations are shown in Figure 1-5. At this point, the MYSQL part has been completed. (Note that it is added in the test library. For QT, test should be selected;

#1) Copy libmysql.dll and libmysqld.dll in the lib directory of the mysql-5.6 file to the bin file of mingw493_32 in Qt5.5. Shown in Figure 1-6; Name the project sql_test;

Add QT =sql

main.cpp in the sql_test.pro file and change it to

 1 #include <QCoreApplication> 2 #include <QSqlDatabase> 3 #include <QSqlQuery> 4 #include <QSqlError> 5 #include <QtDebug> 6 void connect_mysql() 7 { 8     QSqlDatabase db=QSqlDatabase::addDatabase("QMYSQL"); 9        db.setHostName("127.0.0.1");      //连接数据库主机名，这里需要注意（若填的为”127.0.0.1“，出现不能连接，则改为localhost)10        db.setPort(3306);                 //连接数据库端口号，与设置一致11         db.setDatabaseName("test");      //连接数据库名，与设置一致12         db.setUserName("root");          //数据库用户名，与设置一致13         db.setPassword("88888888");    //数据库密码，与设置一致14         db.open();15         if(!db.open())16         {17             qDebug()<<"不能连接"<<"connect to mysql error"<<db.lastError().text();18             return ;19         }20         else21         {22              qDebug()<<"连接成功"<<"connect to mysql OK";23         }24         QSqlQuery query(db);25         query.exec("select * from student");26         while(query.next()){27             qDebug()<<query.value("name").toString();28         }29 }30 int main(int argc,char *argv[])31 {32     QCoreApplication a(argc,argv);33     connect_mysql();34     return a.exec();35 }

3) Test results

                                                                                                                                                                                          Figure 1-7

The results show that QT has successfully read the student table in MYSQL.

The project can be downloaded at https://github.com/xtuwang/Qt_Project/tree/xtuwang-patch-1.

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