Question

C++ SQLite3 how to know if select return 0 rows

I have a select statement for SQLite3, how do I know that if after executing the sql statement, the result is 0 rows , no match found etc..

How can i modify my code so that if 0 rows found, it will not execute the part where it put the result into a vector.

My code below:

sqlstatement = "SELECT * from abe_account where department="+quotesql(department)+" AND name="+quotesql(name)+";";


    std::vector< std::vector < std:: string > > result;
    for( int i = 0; i < 4; i++ )
    result.push_back(std::vector< std::string >());


    sqlite3_prepare( db, sqlstatement.c_str() , -1, &stmt2, NULL );//preparing the statement
    sqlite3_step( stmt2 );//executing the statement

    while( sqlite3_column_text( stmt2, 0 ) )
{
    for( int i = 0; i < 4; i++ )
    result[i].push_back( std::string( (char *)sqlite3_column_text( stmt2, i ) ) );
    sqlite3_step( stmt2 );
    counter ++;
}

Answer 1

sqlite3_step returns SQLITE_DONE when there are no (more) rows to process:

int stat = sqlite3_step(stmt2);
if (stat == SQLITE_DONE) {
    // no rows to process
}

Remember to check for errors as well, e.g.:

if (stat != SQLITE_DONE && stat != SQLITE_ROW) {
    // there's probably a problem
}

You can find the complete list of result codes in the manual.

Lastly, you should use the “v2” interface when using SQLite3. From the manual:

The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are recommended for all new programs. The two older interfaces are retained for backwards compatibility, but their use is discouraged.