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Minor improvement of example1 to demonstrate variable reuse

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Sébastien Rombauts 2015-04-28 20:08:38 +02:00
parent 29a9645314
commit 82364ea419
1 changed files with 40 additions and 33 deletions
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61
examples/example1/main.cpp
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@ -2,7 +2,7 @@
* @file main.cpp
* @brief A few short examples in a row.
*
* Demonstrate how-to use the SQLite++ wrapper
* Demonstrates how-to use the SQLite++ wrapper
*
* Copyright (c) 2012-2014 Sebastien Rombauts (sebastien.rombauts@gmail.com)
*
@ -91,7 +91,7 @@ int main ()
std::cout << "SQLite database file '" << db.getFilename().c_str() << "' opened successfully\n";
// Test if the 'test' table exists
bool bExists = db.tableExists("test");
const bool bExists = db.tableExists("test");
std::cout << "SQLite table 'test' exists=" << bExists << "\n";
// Get a single value result with an easy to use shortcut
@ -105,49 +105,56 @@ int main ()
query.bind(1, 2);
std::cout << "binded with integer value '2' :\n";
// Loop to execute the query step by step, to get one a row of results at a time
while (query.executeStep())
{
// Demonstrate how to get some typed column value (and the equivalent explicit call)
int id = query.getColumn(0); // = query.getColumn(0).getInt()
//const char* pvalue = query.getColumn(1); // = query.getColumn(1).getText()
std::string value2 = query.getColumn(1); // = query.getColumn(1).getText()
int bytes = query.getColumn(1).getBytes();
double weight = query.getColumn(2); // = query.getColumn(2).getInt()
static bool bFirst = true;
if (bFirst)
// Execute the first step of the query, to get the fist row of results, and name of columns
if (query.executeStep())
{
// Show how to get the aliased names of the result columns.
std::string name0 = query.getColumn(0).getName();
std::string name1 = query.getColumn(1).getName();
std::string name2 = query.getColumn(2).getName();
const std::string name0 = query.getColumn(0).getName();
const std::string name1 = query.getColumn(1).getName();
const std::string name2 = query.getColumn(2).getName();
std::cout << "aliased result [\"" << name0.c_str() << "\", \"" << name1.c_str() << "\", \"" << name2.c_str() << "\"]\n";
#ifdef SQLITE_ENABLE_COLUMN_METADATA
// Show how to get origin names of the table columns from which theses result columns come from.
// Requires the SQLITE_ENABLE_COLUMN_METADATA preprocessor macro to be
// also defined at compile times of the SQLite library itself.
name0 = query.getColumn(0).getOriginName();
name1 = query.getColumn(1).getOriginName();
name2 = query.getColumn(2).getOriginName();
std::cout << "origin table 'test' [\"" << name0.c_str() << "\", \"" << name1.c_str() << "\", \"" << name2.c_str() << "\"]\n";
const std::string oname0 = query.getColumn(0).getOriginName();
const std::string oname1 = query.getColumn(1).getOriginName();
const std::string oname2 = query.getColumn(2).getOriginName();
std::cout << "origin table 'test' [\"" << oname0.c_str() << "\", \"" << oname1.c_str() << "\", \"" << oname2.c_str() << "\"]\n";
#endif
bFirst = false;
}
// Demonstrates how to get some typed column value (and the equivalent explicit call)
const int id = query.getColumn(0); // = query.getColumn(0).getInt()
//const char* pvalue = query.getColumn(1); // = query.getColumn(1).getText()
const std::string value2 = query.getColumn(1); // = query.getColumn(1).getText()
const int bytes = query.getColumn(1).getBytes();
const double weight = query.getColumn(2); // = query.getColumn(2).getInt()
std::cout << "row (" << id << ", \"" << value2.c_str() << "\" " << bytes << " bytes, " << weight << ")\n";
}
// Loop to execute the query step by step, to get one a row of results at a time
while (query.executeStep())
{
// Demonstrates that inserting column value in a std:ostream is natural
std::cout << "row (" << query.getColumn(0) << ", \"" << query.getColumn(1) << "\", " << query.getColumn(2) << ")\n";
}
// Reset the query to use it again
query.reset();
std::cout << "SQLite statement '" << query.getQuery().c_str() << "' reseted (" << query.getColumnCount () << " columns in the result)\n";
// Bind the string value "6" to the first parameter of the SQL query
query.bind(1, "6");
std::cout << "binded with string value \"6\" :\n";
// Reuses variables: uses assignement operator in the loop instead of constructor with initialization
int id = 0;
std::string value2;
double weight = 0.0;
while (query.executeStep())
{
// Demonstrate that inserting column value in a std:ostream is natural
std::cout << "row (" << query.getColumn(0) << ", \"" << query.getColumn(1) << "\", " << query.getColumn(2) << ")\n";
id = query.getColumn(0); // = query.getColumn(0).getInt()
value2 = query.getColumn(1); // = query.getColumn(1).getText()
weight = query.getColumn(2); // = query.getColumn(1).getInt()
std::cout << "row (" << id << ", \"" << value2 << "\", " << weight << ")\n";
}
}
catch (std::exception& e)
@ -163,7 +170,7 @@ int main ()
// Open the database and compile the query
Example example;
// Demonstrate the way to use the same query with different parameter values
// Demonstrates the way to use the same query with different parameter values
example.ListGreaterThan(8);
example.ListGreaterThan(6);
example.ListGreaterThan(2);