ImportModel::defineTables PHP Method

    public function defineTables()
    {
        $St = Gdn::structure();
        $DestStructure = clone $St;
        $Tables =& $this->tables();
        foreach ($Tables as $Table => $TableInfo) {
            $Columns = $TableInfo['Columns'];
            if (!is_array($Columns) || count($Columns) == 0) {
                throw new Gdn_UserException(sprintf(t('The %s table is not in the correct format.', $Table)));
            }
            $St->table(self::TABLE_PREFIX . $Table);
            // Get the structure from the destination database to match types.
            try {
                $DestStructure->reset()->get($Table);
            } catch (Exception $Ex) {
                // Trying to import into a non-existant table.
                $Tables[$Table]['Skip'] = true;
                continue;
            }
            //$DestColumns = $DestStructure->Columns();
            $DestModified = false;
            foreach ($Columns as $Name => $Type) {
                if (!$Name) {
                    throw new Gdn_UserException(sprintf(t('The %s table is not in the correct format.'), $Table));
                }
                if ($DestStructure->columnExists($Name)) {
                    $StructureType = $DestStructure->columnTypeString($DestStructure->columns($Name));
                } elseif ($DestStructure->columnExists($Type)) {
                    // Fix the table definition.
                    unset($Tables[$Table]['Columns'][$Name]);
                    $Tables[$Table]['Columns'][$Type] = '';
                    $Name = $Type;
                    $StructureType = $DestStructure->columnTypeString($DestStructure->columns($Type));
                } elseif (!stringBeginsWith($Name, '_')) {
                    $StructureType = $Type;
                    if (!$StructureType) {
                        $StructureType = 'varchar(255)';
                    }
                    // This is a new column so it needs to be added to the destination table too.
                    $DestStructure->column($Name, $StructureType, null);
                    $DestModified = true;
                } elseif ($Type) {
                    $StructureType = $Type;
                } else {
                    $StructureType = 'varchar(255)';
                }
                $St->column($Name, $StructureType, null);
            }
            // Add a new ID column.
            if (array_key_exists($Table . 'ID', $Columns)) {
                $St->column('_NewID', $DestStructure->columnTypeString($Table . 'ID'), null)->column('_Action', array('Insert', 'Update'), null);
            }
            try {
                if (!$this->isDbSource()) {
                    $St->set(true, true);
                } else {
                    $St->reset();
                }
                if ($DestModified) {
                    $DestStructure->set();
                }
            } catch (Exception $Ex) {
                // Since these exceptions are likely caused by a faulty import file they should be considered user exceptions.
                throw new Gdn_UserException(sprintf(t('There was an error while trying to create the %s table (%s).'), $Table, $Ex->getMessage()));
                //, $Ex);
            }
        }
        return true;
    }