Explain the link of the Qt database and how to use SQL

Qt DatabaseLink and how to useSQLIs the content to be introduced in this article, mainly to learnQTMediumDatabaseAndSQLFor more information about how to use it, see this article.

I have never been in touch with the database. I suddenly had the opportunity to use MySQL for the first time. I just learned SQL syntax and learned how to use Qt in combination with the database, by the way, I tried to connect the database to Qt and use SQL. I won't talk about the SQL part, and Qt will talk about the link part first.

1. database-driven first

Now, Qt SDk for release converts LibMySQL. lib in MySQL/opt to. a. You can skip this step by using MSVC ). Then go to qt/src/plugins/sqldriver/mysql to compile the driver.

 
 

  
  
QMAKE -o Makefile "INCLUDEPATH+=MYSQL/INCLUDE" "LIBS+=MYSQL/LIB/OPT/libmysql.a" mysql.pro 
 
 

Pay attention to the qmake parameter and make it again. This part is described in detail on the Internet,

2. Use SQL in Qt

Mainly the following classes

QSqlDatabase is built on the Database Link
 
QSqlQuery is used to execute SQL statements.
 
QSqlTableModel combined with QTableView can output database tables

Paste the simple Demo I wrote

 
 

  
  
QSqlDatabase db = QSqlDatabase: addDatabase ("QMYSQL"/* "QODBC" */); // becomes the new default connection
  
  
Db. setUserName ("root"); // User Name
  
  
Db. setPassword ("password"); // password
  
  
Db. setHostName ("localhost ");
  
  
Db. setDatabaseName ("test"); // Database Name
  
  
Db. setConnectOptions ("CLIENT_SSL = 1; CLIENT_IGNORE_SPACE = 1"); // use SSL
  
  
Db. setPort (3306); // Port
  
  
If (db. open ()){
  
  
QDebug () <"open/n" <db. lastError (). driverText () <"/n ";
  
  
}
  
  
Else {
  
  
QDebug () <"open faile/n ";
  
  
}
  
  
QSqlQuery query; // used to execute the SQL language
  
  
Query.exe c ("show databases"); // very convenient
  
  
While (query. next ()){
  
  
QDebug () <query. value (0). toString () <"/n ";
  
  
}
  
  
 
  
  
QSqlTableModel * model = new QSqlTableModel; // indirectly load the database table into QTableView
  
  
Model-> setTable ("people"); // table name
  
  
Model-> setEditStrategy (QSqlTableModel: OnManualSubmit );
  
  
Model-> select ();
  
  
// Model-> removeColumn (0); // don't show the ID
  
  
// Model-> setHeaderData (0, Qt: Horizontal, QObject: tr ("ID "));
  
  
Model-> setHeaderData (0, Qt: Horizontal, tr ("Name "));
  
  
Model-> setHeaderData (1, Qt: Horizontal, tr ("Age "));
  
  
Model-> setHeaderData (2, Qt: Horizontal, tr ("Sex "));
  
  
 
  
  
QTableView * view = new QTableView (this );
  
  
View-> setModel (model );
  
  
Db. close ();
  
  
QGridLayout * gl = new QGridLayout ();
  
  
Gl-> addWidget (view );
  
  
This-> setLayout (gl );
 
 

Summary: DetailsQt DatabaseLink and how to useSQLI hope this article will help you!