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This article mainly introduces "what is the method of setting up the Qt database". In the daily operation, I believe that many people have doubts about the method of setting up the Qt database. The editor consulted all kinds of materials and sorted out a simple and easy-to-use operation method. I hope it will be helpful for you to answer the doubt of "what is the method of setting up the Qt database?" Next, please follow the editor to study!

I. Preface

As a management system, the database must be indispensable. Qt's built-in sqlite database is already sufficient, and I can personally test that the amount of data can support 100 million levels, rather than 10 million levels as many people say on the Internet. I have simulated more than 100 million pieces of data, and I can still query it very well, and it is still in a table, but the single file is so large, with more than 2G, and the performance is definitely worse than millions of items. But this kind of 100 million level situation is still very rare, it is also recommended to store to the 10 million level, more than do automatic cleaning of early data.

For compatibility and expansibility, the system not only supports the default sqlite database, but also supports mysql database, as for sql server database, PostgreSQL database, etc., all have made corresponding interfaces, which have not been tested. At present, more than 30 Qt versions and various VS versions have been installed on the computer. Enough, there are no plans to install several other databases for testing. This multi-database switching support function Mainly in the Qt encapsulated database class, I have to say that this is the work of Qt, the only thing to pay attention to is the subtle differences between various databases, such as query records, time range conditions, sqlite uses datetime (StartTime), and mysql uses unix_timestamp (StartTime), this subtle difference can be written in the specific code to determine the processing.

In the place where the database is set up, two buttons are specially added, one is the connection test, which is used to test whether the database server is connected, and to judge whether the database server information is correct. All database client software also have this function, which ensures that incorrect information can be excluded at the filling stage. Another button is to initialize the database, the function is to execute the sql script to generate a new database file, he first deletes the original database, and then executes the script to generate a new database file.

II. Functional features

Collect data port, support serial port + network port, serial port support free setting of serial number + baud rate, network support free setting of IP address + communication port, each port supports collection cycle, default one address per second, support setting communication timeout times, default 3 times, support maximum reconnection time, used to re-read offline devices.

Controller information, you can add the controller name, select the controller address + controller model, and set the number of detectors under the controller.

Detector information, can add tag, free to choose detector type, gas type, gas symbol, high reported value, low reported value, buffer value, clear zero value, whether enabled, alarm sound, background map, storage cycle, numerical conversion decimal places, alarm delay time, alarm type (HH,LL,HL) and so on.

Controller model + detector type + gas type + gas symbol, all can be configured freely.

Maps can be imported and deleted, and all detectors can be dragged and saved freely.

Port information + controller information + detector information, support import and export + export to excel+ printing.

Run record + alarm record + user record, support multi-condition combination query, such as time period + controller + detector, etc., all records can be exported to excel+ printing.

Records exported to excel support all versions of table files such as excel+wps and do not rely on software such as excel.

You can delete data within a specified time range, support automatic cleaning of early data, and set the maximum number of saved records.

Support alarm short message forwarding, support multiple receiving mobile phone numbers, you can set the sending interval, such as instant sending or sending all alarm messages once every 6 hours, the text message content is too long, automatically split multiple text messages.

Support alarm email forwarding, support multiple receiving mailboxes, can set sending interval, such as immediate sending or sending all alarm messages once every 6 hours, support attachment sending.

Overreport color + underreport color + normal color + 0 value color + curve background + curve color, etc., are free to choose.

The Chinese title + English title + logo path + copyright of the software can be set freely.

Provide switch settings for boot operation + alarm sound + automatic login + remember password and so on.

Alarm sound can be set to play the number of times, the interface provides 17 kinds of skin file selection.

Cloud data synchronization is supported, and the information of cloud database can be set, such as database name, user name + password, etc.

Support network forwarding and network reception, after the network reception is turned on, the software receives data from udp for analysis. Network forwarding supports multiple target IP, so it realizes the software of local collection, and freely transfers the data to the client to view the detector data at any time.

Automatically remember the user's last stay in the interface + other information, restart and apply automatically.

The alarm automatically switches to the corresponding map, and the detector button flashes.

Double-click the detector icon to control it back.

Support user rights management, administrator + operator two categories, user login + user exit, can remember the password and automatic login, more than three error messages and close the program.

Support four monitoring modes, equipment panel monitoring + map monitoring + table data monitoring + curve data monitoring, free to switch, four synchronous applications.

Support alarm relay linkage, a tag can link multiple modules and relay numbers across serial ports, and support many-to-many.

The local data store supports sqlite+mysql and remote data synchronization to the cloud database. Automatically reconnect.

The data collected by the local device is uploaded to the cloud in real time so that it can be extracted by other methods such as APP or web.

Two kinds of data sources are supported, one is serial port and network to collect equipment data through protocol, the other is database collection. The database acquisition mode can be used as a general system.

Comes with a device simulation tool that supports 16 device data simulations, as well as database data simulations to test data when there is no device.

The default communication protocol uses modbus protocol, and later increases the support of mqtt and other Internet of things protocols to make a general system.

Supports all windows operating systems + linux operating systems and other operating systems.

Third, effect picture

4. Core code # pragma execution_character_set ("utf-8") # include "dblocalthread.h" QScopedPointer DbLocalThread::self;DbLocalThread * DbLocalThread::Instance () {if (self.isNull ()) {static QMutex mutex; QMutexLocker locker (& mutex); if (self.isNull ()) {self.reset (new DbLocalThread);}} return self.data () } DbLocalThread::DbLocalThread (QObject * parent): QThread (parent) {stopped = false; dbOkLocal = false; errorCount = 0; lastCheckTimeLocal = QDateTime::currentDateTime (); checkConn = false; checkInterval = 30; dbTypeLocal = DbType_MySql; connNameLocal = "qt_sql_default_connection"; hostNameLocal = "127.0.0.1"; portLocal = 3306; dbNameLocal = "db_mysql"; userNameLocal = "root"; userPwdLocal = "root" } DbLocalThread::~DbLocalThread () {this- > stop (); this- > wait ();} void DbLocalThread::run () {while (! stopped) {/ / perform a regular verification of the database connection QDateTime now = QDateTime::currentDateTime (); if (checkConn & & lastCheckTimeLocal.secsTo (now) > = checkInterval) {checkDb (); lastCheckTimeLocal = now; continue } / / process the data if the database connection is normal, and reconnect the database if (! dbOkLocal & & errorCount > = 3) {closeDb (); msleep (3000); openDb (); emit debug (QString ("reconnect local database% 1") .arg (dbOkLocal? "success": "failure"); msleep (3000);} else {msleep (3000);}} stopped = false;} bool DbLocalThread::openDb () {/ / you can add if (dbTypeLocal = = DbType_Sqlite) {dbConnLocal = QSqlDatabase::addDatabase ("QSQLITE", connNameLocal); dbConnLocal.setDatabaseName (dbNameLocal) to other databases } else if (dbTypeLocal = = DbType_MySql) {dbConnLocal = QSqlDatabase::addDatabase ("QMYSQL", connNameLocal); dbConnLocal.setConnectOptions ("MYSQL_OPT_RECONNECT=1;MYSQL_OPT_CONNECT_TIMEOUT=1;MYSQL_OPT_READ_TIMEOUT=1;MYSQL_OPT_WRITE_TIMEOUT=1"); dbConnLocal.setHostName (hostNameLocal); dbConnLocal.setPort (portLocal); dbConnLocal.setDatabaseName (dbNameLocal); dbConnLocal.setUserName (userNameLocal); dbConnLocal.setPassword (userPwdLocal) } errorCount = 0; dbOkLocal = dbConnLocal.open (); return dbOkLocal;} bool DbLocalThread::checkDb () {QDateTime dtStart = QDateTime::currentDateTime (); QString sql = "select 1"; QSqlQuery query (dbConnLocal); dbOkLocal = query.exec (sql); dbOkLocal? (errorCount = 0): errorCount++; QDateTime dtEnd = QDateTime::currentDateTime (); double ms = dtStart.msecsTo (dtEnd); emit debug ("check local database connections (% 1 / usage% 2 seconds)"). Arg (1) .arg (QString::number (ms / 1000, 'fags, 3)); return dbOkLocal;} void DbLocalThread::closeDb () {dbConnLocal.close (); QSqlDatabase::removeDatabase (connNameLocal); dbOkLocal = false Emit debug ("shut down the local database");} void DbLocalThread::stop () {stopped = true;} void DbLocalThread::setConnInfo (DbLocalThread::DbType dbType, const QString & connName, const QString & hostName, int port, const QString & dbName, const QString & userName, const QString & userPwd) {this- > dbTypeLocal = dbType; this- > connNameLocal = connName; this- > hostNameLocal = hostName; this- > portLocal = port; this- > dbNameLocal = dbName; this- > userNameLocal = userName; this- > userPwdLocal = userPwd } void DbLocalThread::setCheckConn (bool checkConn) {this- > checkConn = checkConn;} void DbLocalThread::setCheckInterval (int checkInterval) {if (checkInterval > 5 & & this- > checkInterval! = checkInterval) {this- > checkInterval = checkInterval;}} QSqlDatabase DbLocalThread::getDb () {return dbConnLocal;} bool DbLocalThread::getOk () {return dbOkLocal;} at this point, the study of "what is the method of Qt database setting" is over, hoping to solve everyone's doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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