Thermodynamic processes calculator is a simple application that only counts thermodynamic changes of humid air in some cases but it still needed SQL or CSV table to finish calculations. In calculations of a point after cooling process the application needs a table where it can find temperature regard vapor pressure with that data:

I assumed that it is the best if I use SQLite to accomplish that. That SQL implementation doesn’t need any server application, it uses only one file. I prepared the file with SQLite DB Browser.

The hardest task came after that. How to implement SQLite query in my application despite I am completely new in SQLite. I made some research and I found some useful libraries to do that. In my opinion the best option is SQLiteC++ library. It is complete object objected code with exceptions handling. Unfortunately I had some problems with implementing it in my application, but this is normal 🙂 I solve these problems with help of uncle GOOGlE :).

I wanted it to be useful on GNU/Linux and on Windows, unfortunately I don’t know yet how to make DLLs so I just added the files to building tree of my application. Also with sqlite3 source files. I bundled all files in to one folder and Then I changed all includes as local:

#include <SQLiteCpp/Assertion.h>
#include <SQLiteCpp/Exception.h>
#include <SQLiteCpp/Database.h>
#include <SQLiteCpp/Statement.h>
#include <SQLiteCpp/Column.h>
#include <SQLiteCpp/Transaction.h>

for

#include "assertion.h"
#include "exception.h"
#include "database.h"
#include "statement.h"
#include "column.h"
#include "transaction.h"

That is example only from file SQLiteCpp.h, I had to change like this all files – headers and source files.

Also I added in .pro file one line:

unix:!macx: LIBS += -ldl

And it can be compiled under GNU/Linux and under Windows 10 as well.

Then I changed a little bit sample query from the project github site like this:

try {
	// Open a database file
	SQLite::Database db("temperature.db");

	// Compile a SQL query, containing one parameter (index 1)
	SQLite::Statement query(db, "SELECT temperature FROM temperature ORDER BY ABS(? - vapor) LIMIT 1");

	// Bind the integer value 6 to the first parameter of the SQL query
	query.bind(1, equilibriumVaporPoint);

	// Loop to execute the query step by step, to get rows of result
	query.executeStep();
	temperature = query.getColumn(0);
}
catch (std::exception& e) {
	std::cerr << "exception: " << e.what() << std::endl;
}