Doctrine\DBAL\Platforms\PostgreSqlPlatform::getAlterTableSQL PHP Method

    public function getAlterTableSQL(TableDiff $diff)
    {
        $sql = array();
        $commentsSQL = array();
        $columnSql = array();
        foreach ($diff->addedColumns as $column) {
            if ($this->onSchemaAlterTableAddColumn($column, $diff, $columnSql)) {
                continue;
            }
            $query = 'ADD ' . $this->getColumnDeclarationSQL($column->getQuotedName($this), $column->toArray());
            $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' ' . $query;
            $comment = $this->getColumnComment($column);
            if (null !== $comment && '' !== $comment) {
                $commentsSQL[] = $this->getCommentOnColumnSQL($diff->getName($this)->getQuotedName($this), $column->getQuotedName($this), $comment);
            }
        }
        foreach ($diff->removedColumns as $column) {
            if ($this->onSchemaAlterTableRemoveColumn($column, $diff, $columnSql)) {
                continue;
            }
            $query = 'DROP ' . $column->getQuotedName($this);
            $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' ' . $query;
        }
        foreach ($diff->changedColumns as $columnDiff) {
            /** @var $columnDiff \Doctrine\DBAL\Schema\ColumnDiff */
            if ($this->onSchemaAlterTableChangeColumn($columnDiff, $diff, $columnSql)) {
                continue;
            }
            if ($this->isUnchangedBinaryColumn($columnDiff)) {
                continue;
            }
            $oldColumnName = $columnDiff->getOldColumnName()->getQuotedName($this);
            $column = $columnDiff->column;
            if ($columnDiff->hasChanged('type') || $columnDiff->hasChanged('precision') || $columnDiff->hasChanged('scale') || $columnDiff->hasChanged('fixed')) {
                $type = $column->getType();
                // here was a server version check before, but DBAL API does not support this anymore.
                $query = 'ALTER ' . $oldColumnName . ' TYPE ' . $type->getSQLDeclaration($column->toArray(), $this);
                $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' ' . $query;
            }
            if ($columnDiff->hasChanged('default') || $columnDiff->hasChanged('type')) {
                $defaultClause = null === $column->getDefault() ? ' DROP DEFAULT' : ' SET' . $this->getDefaultValueDeclarationSQL($column->toArray());
                $query = 'ALTER ' . $oldColumnName . $defaultClause;
                $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' ' . $query;
            }
            if ($columnDiff->hasChanged('notnull')) {
                $query = 'ALTER ' . $oldColumnName . ' ' . ($column->getNotnull() ? 'SET' : 'DROP') . ' NOT NULL';
                $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' ' . $query;
            }
            if ($columnDiff->hasChanged('autoincrement')) {
                if ($column->getAutoincrement()) {
                    // add autoincrement
                    $seqName = $this->getIdentitySequenceName($diff->name, $oldColumnName);
                    $sql[] = "CREATE SEQUENCE " . $seqName;
                    $sql[] = "SELECT setval('" . $seqName . "', (SELECT MAX(" . $oldColumnName . ") FROM " . $diff->getName($this)->getQuotedName($this) . "))";
                    $query = "ALTER " . $oldColumnName . " SET DEFAULT nextval('" . $seqName . "')";
                    $sql[] = "ALTER TABLE " . $diff->getName($this)->getQuotedName($this) . " " . $query;
                } else {
                    // Drop autoincrement, but do NOT drop the sequence. It might be re-used by other tables or have
                    $query = "ALTER " . $oldColumnName . " " . "DROP DEFAULT";
                    $sql[] = "ALTER TABLE " . $diff->getName($this)->getQuotedName($this) . " " . $query;
                }
            }
            if ($columnDiff->hasChanged('comment')) {
                $commentsSQL[] = $this->getCommentOnColumnSQL($diff->getName($this)->getQuotedName($this), $column->getQuotedName($this), $this->getColumnComment($column));
            }
            if ($columnDiff->hasChanged('length')) {
                $query = 'ALTER ' . $oldColumnName . ' TYPE ' . $column->getType()->getSQLDeclaration($column->toArray(), $this);
                $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' ' . $query;
            }
        }
        foreach ($diff->renamedColumns as $oldColumnName => $column) {
            if ($this->onSchemaAlterTableRenameColumn($oldColumnName, $column, $diff, $columnSql)) {
                continue;
            }
            $oldColumnName = new Identifier($oldColumnName);
            $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' RENAME COLUMN ' . $oldColumnName->getQuotedName($this) . ' TO ' . $column->getQuotedName($this);
        }
        $tableSql = array();
        if (!$this->onSchemaAlterTable($diff, $tableSql)) {
            $sql = array_merge($sql, $commentsSQL);
            if ($diff->newName !== false) {
                $sql[] = 'ALTER TABLE ' . $diff->getName($this)->getQuotedName($this) . ' RENAME TO ' . $diff->getNewName()->getQuotedName($this);
            }
            $sql = array_merge($this->getPreAlterTableIndexForeignKeySQL($diff), $sql, $this->getPostAlterTableIndexForeignKeySQL($diff));
        }
        return array_merge($sql, $tableSql, $columnSql);
    }