系統版本 : Centos7
QT VERSION : 5.6
測試代碼:
#include <iostream>
using namespace std;
#include <QApplication>
#include "gui/mainwindow.h"
#include <QSqlDatabase>
#include <QDebug>
#include <QSqlError>
#include <QSqlQuery>
using namespace std;
int main (int argc, char **argv) {
//輸出可用數據庫
QCoreApplication::addLibraryPath("/home/njq/dev_env/Qt5.6.0/5.6/gcc_64/plugins/sqldrivers");
qDebug()<<"available drivers:";
QStringList drivers = QSqlDatabase::drivers();
foreach(QString driver, drivers)
qDebug()<<driver;
//打開MySQL
QSqlDatabase data_base = QSqlDatabase::addDatabase("QMYSQL");
data_base.setHostName("192.168.0.200"); //設置主機地址
data_base.setPort(3306); //設置端口
data_base.setDatabaseName("alarmcenter"); //設置數據庫名稱
data_base.setUserName("root"); //設置用戶名
data_base.setPassword("root"); //設置密碼
if(!data_base.open())
qDebug()<<"failed to connect to mysql" << data_base.lastError ().text ();
else {
qDebug()<<"success";
QString strSQL = "SELECT alarm_id FROM alarm;";
QSqlQuery sql_query;
sql_query.prepare (strSQL);
sql_query.exec ();
while (sql_query.next ()) {
int id = sql_query.value (0).toInt ();
qDebug () << id;
}
}
}
出現瞭如下的錯誤:
QSqlDatabase: MYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QMYSQL QMYSQL3 QPSQL QPSQL7
QSqlDatabase: an instance of QCoreApplication is required for loading driver plugins
failed to connect to mysql "Driver not loaded Driver not loaded"
查看QT的安裝目錄
~/dev_env/Qt5.6.0/5.6/gcc_64/plugins/sqldrivers
有一個文件:
libqsqlmysql.so
使用ldd命令檢查下依賴
[xxx@localhost sqldrivers]$ ldd libqsqlmysql.so
linux-vdso.so.1 => (0x00007ffcf65b4000)
libmysqlclient_r.so.16 => not found
libz.so.1 => /lib64/libz.so.1 (0x00007f452c898000)
看到 libmysqlclient_r.so.16 這個so文件的依賴沒有找到
通過查找資料,發現如下解決辦法
先安裝MYSQL的開發環境
[njq@localhost sqldrivers]$ sudo yum install mysql-devel
重新編譯mysql驅動
[njq@localhost mysql]$ cd ~/dev_env/Qt5.6.0/5.6/Src/qtbase/src/plugins/sqldrivers/mysql
[xxx@localhost mysql]$ ~/dev_env/Qt5.6.0/5.6/gcc_64/bin/qmake #因爲沒有配置qmake路徑,所以用了全路徑
[xxx@localhost mysql]$ make
看到編譯後的最後一行
mv -f libqsqlmysql.so ../../../../plugins/sqldrivers/
把這個生成的libqsqlmysql.so覆蓋到......./Qt5.6.0/5.6/gcc_64/plugins/sqldrivers
[xxx@localhost sqldrivers]$ mv libqsqlmysql.so ~/dev_env/Qt5.6.0/5.6/gcc_64/plugins/sqldrivers/
然後再查看libqsqlmysql.so的依賴
[xxx@localhost sqldrivers]$ ldd libqsqlmysql.so
linux-vdso.so.1 => (0x00007fffc437c000)
libmysqlclient.so.18 => /usr/lib64/mysql/libmysqlclient.so.18 (0x00007f3de67bc000)
libz.so.1 => /lib64/libz.so.1 (0x00007f3de65a5000)
libcrypt.so.1 => /lib64/libcrypt.so.1 (0x00007f3de636e000)
libnsl.so.1 => /lib64/libnsl.so.1 (0x00007f3de6155000)
libssl.so.10 => /lib64/libssl.so.10 (0x00007f3de5ee7000)
libcrypto.so.10 => /lib64/libcrypto.so.10 (0x00007f3de5aff000)
libQt5Sql.so.5 => not found
libQt5Core.so.5 => not found
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f3de58e2000)
libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007f3de55da000)
libm.so.6 => /lib64/libm.so.6 (0x00007f3de52d7000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f3de50c1000)
libc.so.6 => /lib64/libc.so.6 (0x00007f3de4d00000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f3de4afb000)
libfreebl3.so => /lib64/libfreebl3.so (0x00007f3de48f8000)
libgssapi_krb5.so.2 => /lib64/libgssapi_krb5.so.2 (0x00007f3de46ac000)
libkrb5.so.3 => /lib64/libkrb5.so.3 (0x00007f3de43c6000)
libcom_err.so.2 => /lib64/libcom_err.so.2 (0x00007f3de41c2000)
libk5crypto.so.3 => /lib64/libk5crypto.so.3 (0x00007f3de3f90000)
/lib64/ld-linux-x86-64.so.2 (0x00007f3de6ee3000)
libkrb5support.so.0 => /lib64/libkrb5support.so.0 (0x00007f3de3d80000)
libkeyutils.so.1 => /lib64/libkeyutils.so.1 (0x00007f3de3b7c000)
libresolv.so.2 => /lib64/libresolv.so.2 (0x00007f3de3962000)
libselinux.so.1 => /lib64/libselinux.so.1 (0x00007f3de373c000)
libpcre.so.1 => /lib64/libpcre.so.1 (0x00007f3de34db000)
liblzma.so.5 => /lib64/liblzma.so.5 (0x00007f3de32b5000)
看到問題已經搞定
重新運行程序,看到如下結果
available drivers:
"QSQLITE"
"QMYSQL"
"QMYSQL3"
"QPSQL"
"QPSQL7"
success
171118
171119
171120
171121
171122
171123
171124
171125
171126
171127
171128
171129
171130
171131
171132
171133
171134
171135
171136