NO_DATA is returned while there is a data

[Igor Korot]

Hi, ALL,

Following code returns MYSQL_NO_DATA for the table where there is definitly a foreign key.

Could someone please explain what I am doing wrong?

Thank you.

    std::wstring cat, table = L"owners", schema = L"draft";
    int result = 0;
    std::wstring query2 = L"SELECT kcu.column_name, kcu.ordinal_position, kcu.referenced_table_schema, kcu.referenced_table_name, kcu.referenced_column_name, rc.update_rule, rc.delete_rule, rc.constraint_name FROM information_schema.key_column_usage kcu, information_schema.referential_constraints rc WHERE kcu.constraint_name = rc.constraint_name AND kcu.table_catalog = ? AND kcu.table_schema = ? AND kcu.table_name = ?;";
    char *col_name[256], ref_schema[256], ref_table[256], ref_column[256], constraint_name[256];
    char update_rule[20], delete_rule[20];
    int ordinal;
    std::map<unsigned long, std::vector<FKField *> > foreign_key;
    unsigned long str_length1, str_length2, str_length3;
    str_length1 = catalog.length() + 2;
    str_length2 = schemaName.length() + 2;
    str_length3 = tableName.length() + 2;
    char *cat = new char[str_length1], *schema = new char[str_length2], *table = new char[str_length3];
    memset( cat, '\0', str_length1);
    memset( schema, '\0', str_length2 );
    memset( table, '\0', str_length3 );
    strcpy( cat, m_pimpl->m_myconv.to_bytes( catalog.c_str() ).c_str() );
    strcpy( schema, m_pimpl->m_myconv.to_bytes( schemaName.c_str() ).c_str() );
    strcpy( table, m_pimpl->m_myconv.to_bytes( tableName.c_str() ).c_str() );
    MYSQL_BIND params[3];
    memset( params, 0, sizeof( params ) );
    auto res1 = mysql_stmt_init( m_db );
    if( !res1 )
    {
        std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) );
        errorMsg.push_back( err );
        result = 1;
    }
    else
    {
        if( mysql_stmt_prepare( res1, m_pimpl->m_myconv.to_bytes( query2.c_str() ).c_str(), query2.length() ) )
        {
            std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) );
            errorMsg.push_back( err );
            result = 1;
        }
        else
        {
            params[0].buffer_type = MYSQL_TYPE_STRING;
            params[0].buffer = (char *) cat;
            params[0].buffer_length = strlen( cat );
            params[0].is_null = 0;
            params[0].length = &str_length1;
            params[1].buffer_type = MYSQL_TYPE_STRING;
            params[1].buffer = (char *) schema;
            params[1].buffer_length = strlen( schema );
            params[1].is_null = 0;
            params[1].length = &str_length2;
            params[2].buffer_type = MYSQL_TYPE_STRING;
            params[2].buffer = (char *) table;
            params[2].buffer_length = strlen( table );
            params[2].is_null = 0;
            params[2].length = &str_length3;
            strcpy( cat, m_pimpl->m_myconv.to_bytes( catalog.c_str() ).c_str() );
            strcpy( schema, m_pimpl->m_myconv.to_bytes( schemaName.c_str() ).c_str() );
            strcpy( table, m_pimpl->m_myconv.to_bytes( tableName.c_str() ).c_str() );
            if( mysql_stmt_bind_param( res1, params ) )
            {
                std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) );
                errorMsg.push_back( err );
                result = 1;
            }
            else
            {
                if( mysql_stmt_execute( res1 ) )
                {
                    std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) );
                    errorMsg.push_back( err );
                    result = 1;
                }
                else
                {
                    MYSQL_BIND results1[8];
                    bool is_null[8], error[8];
                    unsigned long length[8];
                    memset( results1, 0, sizeof( results1 ) );
                    results1[0].buffer_type = MYSQL_TYPE_STRING;
                    results1[0].buffer = &col_name;
                    results1[0].buffer_length = 256;
                    results1[0].is_null = &is_null[0];
                    results1[0].length = &length[0];
                    results1[0].error = &error[0];
                    results1[1].buffer_type = MYSQL_TYPE_SHORT;
                    results1[1].buffer = (char *) &ordinal;
                    results1[1].is_null = &is_null[1];
                    results1[1].error = &error[1];
                    results1[1].length = &length[1];
                    results1[2].buffer_type = MYSQL_TYPE_STRING;
                    results1[2].buffer = &ref_schema;
                    results1[2].buffer_length = 256;
                    results1[2].is_null = &is_null[2];
                    results1[2].length = &length[2];
                    results1[2].error = &error[2];
                    results1[3].buffer_type = MYSQL_TYPE_STRING;
                    results1[3].buffer = &ref_table;
                    results1[3].buffer_length = 256;
                    results1[3].error = &error[3];
                    results1[3].length = &length[3];
                    results1[3].error = &error[3];
                    results1[4].buffer_type = MYSQL_TYPE_STRING;
                    results1[4].buffer = &ref_column;
                    results1[4].buffer_length = 256;
                    results1[4].is_null = &is_null[4];
                    results1[4].length = &length[4];
                    results1[4].error = &error[4];
                    results1[5].buffer_type = MYSQL_TYPE_STRING;
                    results1[5].buffer = &update_rule;
                    results1[5].buffer_length = 20;
                    results1[5].length = &length[5];
                    results1[5].is_null = &is_null[5];
                    results1[5].error = &error[5];
                    results1[6].buffer_type = MYSQL_TYPE_STRING;
                    results1[6].buffer_length = 20;
                    results1[6].buffer = &delete_rule;
                    results1[6].length = &length[6];
                    results1[6].is_null = &is_null[6];
                    results1[6].error = &error[6];
                    results1[7].buffer_type = MYSQL_TYPE_STRING;
                    results1[7].buffer = &constraint_name;
                    results1[7].buffer_length = 256;
                    results1[7].is_null = &is_null[7];
                    results1[7].length = &length[7];
                    results1[7].error = &error[7];
                    if( mysql_stmt_bind_result( res1, results1 ) )
                    {
                        std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) );
                        errorMsg.push_back( err );
                        result = 1;
                    }
                    else
                    {
                        while( true )
                        {
                            auto dataset = mysql_stmt_fetch( res1 );
                            if( dataset == 1 || dataset == MYSQL_NO_DATA )
                                break;
                            else
                            {
                                auto orig_col = m_pimpl->m_myconv.from_bytes( *col_name );
                                auto refCol = m_pimpl->m_myconv.from_bytes( ref_column );
                                auto refSchema = m_pimpl->m_myconv.from_bytes( ref_schema );
                                auto refTable = m_pimpl->m_myconv.from_bytes( ref_table );
                                std::map<int, std::vector<std::wstring> >origFields, refFields;
                                origFields[ordinal].push_back( orig_col );
                                refFields[ordinal].push_back( refCol );
//                                foreign_key[ordinal].push_back( new FKField( ordinal, constraint_name, schemaName, tableName, orig_col, refSchema refTable, refCol, origFields[ordinal], refFields[ordinal], 
                            }
                        }
                        if( mysql_stmt_close( res1 ) )
                        {
                            std::wstring err = m_pimpl->m_myconv.from_bytes( mysql_stmt_error( res1 ) );
                            errorMsg.push_back( err );
                            result = 1;
                        }
                    }
                }
            }
        }
    }