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Editor to share with you how to achieve general database collection in Qt database applications, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

I. Preface

Database collection corresponds to the database synchronization of the previous article. After the database is synchronized to the cloud database, if you want data for app, web pages, Mini Program, etc., you can get the data by executing http requests. The program for receiving and responding to http is generally the easiest to write in php, with a few lines of code. For example, you can build sql statements to be executed according to the requested parameters, and return the results in json form after execution.

There are many ways to do database collection through the Qt program, that is, you can directly connect the database and then bind the database table to QSqlTableModel, and then constantly call the select method to query and refresh the interface, or through the execution of sql statements, through the sql statement form is more flexible, you can first get the data result set, and then filter, such as judging whether the alarm, whether other instructions need to be performed Then send out the form of the needed data signal, and get the needed local correlation signal to the data display, which is equivalent to a layer of screening.

Database communication management thread class features:

The database type can be set and multiple database types are supported.

Database types include but are not limited to odbc, sqlite, mysql, postgresql, sqlserver, oracle, people's Congress, etc.

Database connection information can be set, including host address, user information and so on.

With automatic reconnection mechanism, you can set whether to check the connection and the check interval.

Support a single queue of sql statements, which is generally used to query the returned data, one for each insert and one for execution.

Multiple sql statement queues are supported, which are generally used to submit data remotely, one at a time for execution.

Batch sql statement queues are supported, which are generally used to update data in batches. Multiple bars are inserted and executed at a time.

The maximum number of queues can be set to limit the collection of sql statements processed by the queue.

Print messages, error messages and query results are sent through the signal.

Summary of some experiences in the Development of Qt Database

II. Functional features

At the same time, it supports a variety of databases such as odbc, sqlite, mysql, postgresql, sqlserver, oracle, people's Congress and so on.

A database class can not only manage local database communication, but also support remote database communication.

Database threads support the execution of various sql statements, including individual and batch statements.

All classes in the component print messages, error messages, and execution results are signaled.

Integrated database general page turning class (responsible for specific processing logic), with paging navigation controls (responsible for appearance), to form a super powerful page turning control.

Integrated database automatic cleaning class, set the maximum number of records to automatically clean up early data in the background.

Integrated custom delegate class, supporting check boxes, text boxes, drop-down boxes, date boxes, fine-tuning boxes, progress bars, and so on.

At the same time support Qt4-Qt6, test Qt4.6 to Qt6.3 any version, any system and compiler.

This component is trouble-free 360 days 7 times 24 hours running in at least tens of thousands of sites, commercial grade quality assurance.

Each class corresponds to a complete and detailed usage example, with detailed annotations, which is very suitable for reading and learning.

It can be run as a stand-alone program, such as automatically cleaning up early data and synchronizing data to the cloud.

All threading, no card interface, automatically reconnect the database.

General test case, sqlite database, database generator inserts 1000 records per second for about 0.003 seconds, while automatically cleans up data classes and deletes 1000 records per second for about 0.13s. Different threads do not interfere with each other.

Third, experience address

Experience address: https://pan.baidu.com/s/15ZKAlptW-rDcNq8zlzdYLg extraction code: uyes file name: bin_dbtool.zip

Domestic site: https://gitee.com/feiyangqingyun

International site: https://github.com/feiyangqingyun

4. Effect picture

Related code # include "frmdbdownload.h" # include "ui_frmdbdownload.h" # include "quihelper.h" # include "dbconnthread.h" frmDbDownload::frmDbDownload (QWidget * parent): QWidget (parent), ui (new Ui::frmDbDownload) {ui- > setupUi (this); this- > initForm (); this- > initConfig (); this- > initTable ();} frmDbDownload::~frmDbDownload () {delete ui;} void frmDbDownload::initForm () {ui- > frame- > setFixedWidth (AppConfig::RightWidth) QUIHelper::initTableView (ui- > tableWidget); maxCount = 100; currentCount = 0; columnCount = 0; timer = new QTimer (this); timer- > setInterval (1000); connect (timer, SIGNAL (timeout ()), this, SLOT (on_btnDo_clicked (); / / instantiated database communication class dbConn = new DbConnThread (this); dbConn- > setDbFlag ("cloud") Connect (dbConn, SIGNAL (debug (QString)), this, SLOT (debug (QString); connect (dbConn, SIGNAL (error (QString)), this, SLOT (error (QString); connect (dbConn, SIGNAL (receiveData (QString, QStringList, int), this, SLOT (receiveData (QString, QStringList, int));} void frmDbDownload::initConfig () {ui- > cboxDbType- > addItems (DbHelper::getDbType ()); DbHelper::getDbType > ui- > ui- (ui- > cboxDbType-)) Connect (ui- > cboxDbType, SIGNAL (currentIndexChanged (int)), this, SLOT (saveConfig ()); ui- > txtDbName- > setText (AppConfig::DbName6); connect (ui- > txtDbName, SIGNAL (textChanged (QString)), this, SLOT (saveConfig ()); ui- > txtHostName- > setText (AppConfig::HostName6); connect (ui- > txtHostName, SIGNAL (textChanged (QString)), this, SLOT (saveConfig ()); ui- > txtHostPort- > txtHostPort- (txtHostPort-)) Connect (ui- > txtHostPort, SIGNAL (textChanged (QString)), this, SLOT (saveConfig ()); ui- > txtUserName- > setText (AppConfig::UserName6); connect (ui- > txtUserName, SIGNAL (textChanged (QString)), this, SLOT (saveConfig ()); ui- > txtUserPwd- > setText (AppConfig::UserPwd6); connect (ui- > txtUserPwd, SIGNAL (textChanged (QString), this, SLOT (saveConfig (); void frmDbDownload::saveConfig () {void frmDbDownload::saveConfig = AppConfig::DbType6 > AppConfig::DbType6 > AppConfig::DbType6 () AppConfig::DbName6 = ui- > txtDbName- > text (); AppConfig::HostName6 = ui- > txtHostName- > text (); AppConfig::HostPort6 = ui- > txtHostPort- > text (). ToInt (); AppConfig::UserName6 = ui- > txtUserName- > text (); AppConfig::UserPwd6 = ui- > txtUserPwd- > text (); AppConfig::writeConfig ();} void frmDbDownload::initTable () {QStringList columnNames; columnNames txtMain, 1, msg, maxCount, currentCount) } void frmDbDownload::receiveData (const QString & tag, const QStringList & data, int msec) {QString msg = QString ("time used (% 1 second) identifies (% 2) data (% 3)") .arg (QString::number ((double) msec / 1000, 'fags, 3)) .arg (tag) .arg (data.join ("|")); QUIHelper::appendMsg (ui- > txtMain, 3, msg, maxCount, currentCount) / / display to table int count = data.count (); ui- > tableWidget- > setRowCount (count / columnCount); int row =-1; for (int I = 0; I

TableWidget- > setItem (row, j, new QTableWidgetItem (data.at (I + j));} void frmDbDownload::on_btnOpen_clicked () {if (ui- > btnOpen- > text () = "Open database") {DbInfo dbInfo; dbInfo.connName = this- > objectName (); dbInfo.dbName = AppConfig::DbName6; dbInfo.hostName = AppConfig::HostName6; dbInfo.hostPort = AppConfig::HostPort6 DbInfo.userName = AppConfig::UserName6; dbInfo.userPwd = AppConfig::UserPwd6; QString dbType = AppConfig::DbType6.toUpper (); if (dbType = = "SQLITE") {dbInfo.dbName = DbHelper::getDbDefaultFile ();} dbConn- > setConnInfo (DbHelper::getDbType (dbType), dbInfo); if (dbConn- > openDb ()) {dbConn- > start () Ui- > btnOpen- > setText ("close database");} else {QString error = dbConn- > getDatabase (). LastError (). Text (); QUIHelper::showMessageBoxError ("failed to open database!\ n" + error, 3);}} else {dbConn- > stop (); dbConn- > closeDb (); ui- > btnOpen- > setText ("Open database") On_btnClear_clicked ();} QTimer::singleShot (1000, this, SLOT (on_btnStart_clicked ();} void frmDbDownload::on_btnCopy_clicked () {/ / paste database setting parameters to ui- > cboxDbType- > setCurrentIndex (ui- > cboxDbType- > findText (AppConfig::LocalDbType)); ui- > txtDbName- > setText (AppConfig::LocalDbName); ui- > txtHostName- > setText (AppConfig::LocalHostName) Ui- > txtHostPort- > setText (QString::number (AppConfig::LocalHostPort)); ui- > txtUserName- > setText (AppConfig::LocalUserName); ui- > txtUserPwd- > setText (AppConfig::LocalUserPwd);} void frmDbDownload::on_btnDo_clicked () {if (! dbConn- > getOk ()) {return;} dbConn- > select ("NodeData", "PositionID,NodeValue,NodeStatus,SaveTime") } void frmDbDownload::on_btnStart_clicked () {if (ui- > btnStart- > text () = = "start service") {on_btnDo_clicked (); timer- > start (); ui- > btnStart- > setText ("stop service");} else {timer- > stop (); ui- > btnStart- > setText ("start service") }} void frmDbDownload::on_btnClear_clicked () {QUIHelper::appendMsg (ui- > txtMain, 0, ", maxCount, currentCount);} these are all the contents of the article" how to implement General Database Collection in Qt Database Application ". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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