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The EAVCapture device needs to record its runtime log information. So for easy operation,
I choose the SQLite. It's suitable for the embedded device.
The default database file should be created automatically when the application starts at the first time.
I use the following sql statement to detect if the file is exist.
this->m_database=QSqlDatabase::addDatabase("QSQLITE");
this->m_database.setDatabaseName("EAV.db");
if(!this->m_database.open())
{
qDebug()<<"open sqlite database failed!";
return;
}
//create table.
QSqlQuery tSqlQuery(this->m_database);
if(!tSqlQuery.exec("SELECT COUNT(*) FROM devlog"))
{
//if select is failed,then create the table.
qDebug()<<"start to initial database";
if(!tSqlQuery.exec("CREATE TABLE devlog (CreateTime DATETIME,LogLevel INT,LogMessage BLOB)"))
{
qDebug()<<"create table failes!";
return;
}else{
qDebug()<<"create table success!";
}
}else{
qDebug()<<"database is already exists!";
}
If the file is exist,the sql statement "select count(*) from devlog" should return zero or positive value,
otherwise the exec() function will fails and return false. I can use its return value to know if it is exist.
by zhangshaoyan at May 24,2015 night.
And codes show how to insert a log message:
QString tCreateTime=QDateTime::currentDateTime().toString("yyyy-MM-dd hh:mm:ss");
QString tSqlStatement=QString("INSERT INTO [devlog] ([CreateTime],[LogLevel],[LogMessage]) VALUES ('%1',%2,'%3')").arg(tCreateTime).arg(logLevel).arg(logMessage);
QSqlQuery tSqlQuery;
if(!tSqlQuery.exec(tSqlStatement))
{
return -1;
}
return 0;
（编辑：李大同）
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