postgres7.class.php

来自「很棒的在线教学系统」· PHP 代码 · 共 575 行 · 第 1/2 页

<?php // $Id: postgres7.class.php,v 1.36.2.1 2009/03/02 19:08:26 stronk7 Exp $

///////////////////////////////////////////////////////////////////////////
//                                                                       //
// NOTICE OF COPYRIGHT                                                   //
//                                                                       //
// Moodle - Modular Object-Oriented Dynamic Learning Environment         //
//          http://moodle.com                                            //
//                                                                       //
// Copyright (C) 1999 onwards Martin Dougiamas        http://dougiamas.com  //
//           (C) 2001-3001 Eloy Lafuente (stronk7) http://contiento.com  //
//                                                                       //
// This program is free software; you can redistribute it and/or modify  //
// it under the terms of the GNU General Public License as published by  //
// the Free Software Foundation; either version 2 of the License, or     //
// (at your option) any later version.                                   //
//                                                                       //
// This program is distributed in the hope that it will be useful,       //
// but WITHOUT ANY WARRANTY; without even the implied warranty of        //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         //
// GNU General Public License for more details:                          //
//                                                                       //
//          http://www.gnu.org/copyleft/gpl.html                         //
//                                                                       //
///////////////////////////////////////////////////////////////////////////

/// This class generate SQL code to be used against PostgreSQL
/// It extends XMLDBgenerator so everything can be
/// overriden as needed to generate correct SQL.

class XMLDBpostgres7 extends XMLDBgenerator {

/// Only set values that are different from the defaults present in XMLDBgenerator

    var $number_type = 'NUMERIC';    // Proper type for NUMBER(x) in this DB

    var $unsigned_allowed = false;    // To define in the generator must handle unsigned information
    var $default_for_char = '';      // To define the default to set for NOT NULLs CHARs without default (null=do nothing)

    var $sequence_extra_code = false; //Does the generator need to add extra code to generate the sequence fields
    var $sequence_name = 'BIGSERIAL'; //Particular name for inline sequences in this generator
    var $sequence_name_small = 'SERIAL'; //Particular name for inline sequences in this generator
    var $sequence_only = true; //To avoid to output the rest of the field specs, leaving only the name and the sequence_name variable

    var $rename_table_extra_code = true; //Does the generator need to add code after table rename

    var $rename_column_extra_code = true; //Does the generator need to add code after column rename

    var $enum_inline_code = false; //Does the generator need to add inline code in the column definition

    var $rename_index_sql = 'ALTER TABLE OLDINDEXNAME RENAME TO NEWINDEXNAME'; //SQL sentence to rename one index
                                      //TABLENAME, OLDINDEXNAME, NEWINDEXNAME are dinamically replaced

    var $rename_key_sql = null; //SQL sentence to rename one key (PostgreSQL doesn't support this!)
                                          //TABLENAME, OLDKEYNAME, NEWKEYNAME are dinamically replaced

    /**
     * Creates one new XMLDBpostgres7
     */
    function XMLDBpostgres7() {
        parent::XMLDBgenerator();
        $this->prefix = '';
        $this->reserved_words = $this->getReservedWords();
    }

    /**
     * Given one XMLDB Type, lenght and decimals, returns the DB proper SQL type
     */
    function getTypeSQL ($xmldb_type, $xmldb_length=null, $xmldb_decimals=null) {

        switch ($xmldb_type) {
            case XMLDB_TYPE_INTEGER:    // From http://www.postgresql.org/docs/7.4/interactive/datatype.html
                if (empty($xmldb_length)) {
                    $xmldb_length = 10;
                }
                if ($xmldb_length > 9) {
                    $dbtype = 'BIGINT';
                } else if ($xmldb_length > 4) {
                    $dbtype = 'INTEGER';
                } else {
                    $dbtype = 'SMALLINT';
                }
                break;
            case XMLDB_TYPE_NUMBER:
                $dbtype = $this->number_type;
                if (!empty($xmldb_length)) {
                    $dbtype .= '(' . $xmldb_length;
                    if (!empty($xmldb_decimals)) {
                        $dbtype .= ',' . $xmldb_decimals;
                    }
                    $dbtype .= ')';
                }
                break;
            case XMLDB_TYPE_FLOAT:
                $dbtype = 'DOUBLE PRECISION';
                if (!empty($xmldb_decimals)) {
                    if ($xmldb_decimals < 6) {
                        $dbtype = 'REAL';
                    }
                }
                break;
            case XMLDB_TYPE_CHAR:
                $dbtype = 'VARCHAR';
                if (empty($xmldb_length)) {
                    $xmldb_length='255';
                }
                $dbtype .= '(' . $xmldb_length . ')';
                break;
            case XMLDB_TYPE_TEXT:
                $dbtype = 'TEXT';
                break;
            case XMLDB_TYPE_BINARY:
                $dbtype = 'BYTEA';
                break;
            case XMLDB_TYPE_DATETIME:
                $dbtype = 'TIMESTAMP';
                break;
        }
        return $dbtype;
    }

    /**
     * Returns the code needed to create one enum for the xmldb_table and xmldb_field passes
     */
    function getEnumExtraSQL ($xmldb_table, $xmldb_field) {

        $sql = 'CONSTRAINT ' . $this->getNameForObject($xmldb_table->getName(), $xmldb_field->getName(), 'ck');
        $sql.= ' CHECK (' . $this->getEncQuoted($xmldb_field->getName()) . ' IN (' . implode(', ', $xmldb_field->getEnumValues()) . '))';

        return $sql;
    }

    /**
     * Returns the code (in array) needed to add one comment to the table
     */
    function getCommentSQL ($xmldb_table) {

        $comment = "COMMENT ON TABLE " . $this->getTableName($xmldb_table);
        $comment.= " IS '" . addslashes(substr($xmldb_table->getComment(), 0, 250)) . "'";

        return array($comment);
    }

    /**
     * Returns the code (array of statements) needed to execute extra statements on table rename
     */
    function getRenameTableExtraSQL ($xmldb_table, $newname) {

        $results = array();

        $newt = new XMLDBTable($newname);

        $xmldb_field = new XMLDBField('id'); // Fields having sequences should be exclusively, id.

        $oldseqname = $this->getTableName($xmldb_table) . '_' . $xmldb_field->getName() . '_seq';
        $newseqname = $this->getTableName($newt) . '_' . $xmldb_field->getName() . '_seq';

    /// Rename de sequence
        $results[] = 'ALTER TABLE ' . $oldseqname . ' RENAME TO ' . $newseqname;

    /// Rename all the check constraints in the table
        $oldtablename = $this->getTableName($xmldb_table);
        $newtablename = $this->getTableName($newt);

        $oldconstraintprefix = $this->getNameForObject($xmldb_table->getName(), '');
        $newconstraintprefix = $this->getNameForObject($newt->getName(), '', '');

        if ($constraints = $this->getCheckConstraintsFromDB($xmldb_table)) {
            foreach ($constraints as $constraint) {
            /// Drop the old constraint
                $results[] = 'ALTER TABLE ' . $newtablename . ' DROP CONSTRAINT ' . $constraint->name;
            /// Calculate the new constraint name
                $newconstraintname = str_replace($oldconstraintprefix, $newconstraintprefix, $constraint->name);
            /// Add the new constraint
                $results[] = 'ALTER TABLE ' . $newtablename . ' ADD CONSTRAINT ' . $newconstraintname .
                             ' CHECK ' . $constraint->description;
             }
         }

        return $results;
    }

    /**
     * Given one XMLDBTable and one XMLDBField, return the SQL statements needded to add the field to the table
     * PostgreSQL is pretty standard but with one severe restriction under 7.4 that forces us to overload
     * this function: Default clause is not allowed when adding fields.
     * 
     * This function can be safely removed once min req. for PG will be 8.0
     */
    function getAddFieldSQL($xmldb_table, $xmldb_field) {
    
        $results = array();

        $tablename = $this->getTableName($xmldb_table);
        $fieldname = $this->getEncQuoted($xmldb_field->getName());

        $defaultvalue = null;

    /// Save old flags
        $old_skip_default = $this->alter_column_skip_default;
        $old_skip_notnull = $this->alter_column_skip_notnull;

    /// Prevent default clause and launch parent getAddField()
        $this->alter_column_skip_default = true;
        $this->alter_column_skip_notnull = true;
        $results = parent::getAddFieldSQL($xmldb_table, $xmldb_field);

    /// Re-set old flags
        $this->alter_column_skip_default = $old_skip_default;
        $this->alter_column_skip_notnull = $old_skip_notnull;

    /// Add default (only if not skip_default)
        if (!$this->alter_column_skip_default) {
            if ($defaultclause = $this->getDefaultClause($xmldb_field)) {
                $defaultvalue = $this->getDefaultValue($xmldb_field);
                $results[] = 'ALTER TABLE ' . $tablename . ' ALTER COLUMN ' . $fieldname . ' SET' . $defaultclause; /// Add default clause
            }
        /// Update default value (if exists) to all the records
            if ($defaultvalue !== null) {
                $results[] = 'UPDATE ' . $tablename . ' SET ' . $fieldname . '=' . $defaultvalue;
            }
        }

    /// Add not null (only if no skip_notnull)
        if (!$this->alter_column_skip_notnull) {
            if ($xmldb_field->getNotnull()) {
                $results[] = 'ALTER TABLE ' . $tablename . ' ALTER COLUMN ' . $fieldname . ' SET NOT NULL'; /// Add not null
            }
        }

        return $results;
    }

    /**
     * Given one XMLDBTable and one XMLDBField, return the SQL statements needded to alter the field in the table
     * PostgreSQL has some severe limits:
     *     - Any change of type or precision requires a new temporary column to be created, values to
     *       be transfered potentially casting them, to apply defaults if the column is not null and 
     *       finally, to rename it
     *     - Changes in null/not null require the SET/DROP NOT NULL clause
     *     - Changes in default require the SET/DROP DEFAULT clause
     */
    function getAlterFieldSQL($xmldb_table, $xmldb_field) {

        global $db;

        $results = array(); /// To store all the needed SQL commands

    /// Get the quoted name of the table and field
        $tablename = $this->getTableName($xmldb_table);
        $fieldname = $this->getEncQuoted($xmldb_field->getName());

    /// Take a look to field metadata
        $meta = array_change_key_case($db->MetaColumns($tablename));
        $metac = $meta[$fieldname];
        $oldtype = strtolower($metac->type);
        $oldmetatype = column_type($xmldb_table->getName(), $fieldname);
        $oldlength = $metac->max_length;
        $olddecimals = empty($metac->scale) ? null : $metac->scale;
        $oldnotnull = empty($metac->not_null) ? false : $metac->not_null;
        $olddefault = empty($metac->has_default) ? null : strtok($metac->default_value, ':');

        $typechanged = true;  //By default, assume that the column type has changed
        $precisionchanged = true;  //By default, assume that the column precision has changed
        $decimalchanged = true;  //By default, assume that the column decimal has changed
        $defaultchanged = true;  //By default, assume that the column default has changed
        $notnullchanged = true;  //By default, assume that the column notnull has changed

        $from_temp_fields = false; //By default don't assume we are going to use temporal fields

    /// Detect if we are changing the type of the column
        if (($xmldb_field->getType() == XMLDB_TYPE_INTEGER && substr($oldmetatype, 0, 1) == 'I') ||
            ($xmldb_field->getType() == XMLDB_TYPE_NUMBER  && $oldmetatype == 'N') ||
            ($xmldb_field->getType() == XMLDB_TYPE_FLOAT   && $oldmetatype == 'F') ||
            ($xmldb_field->getType() == XMLDB_TYPE_CHAR    && substr($oldmetatype, 0, 1) == 'C') ||
            ($xmldb_field->getType() == XMLDB_TYPE_TEXT    && substr($oldmetatype, 0, 1) == 'X') ||
            ($xmldb_field->getType() == XMLDB_TYPE_BINARY  && $oldmetatype == 'B')) {
            $typechanged = false;
        }
    /// Detect if we are changing the precision 
        if (($xmldb_field->getType() == XMLDB_TYPE_TEXT) ||
            ($xmldb_field->getType() == XMLDB_TYPE_BINARY) ||
            ($oldlength == -1) ||
            ($xmldb_field->getLength() == $oldlength)) {
            $precisionchanged = false;
        }
    /// Detect if we are changing the decimals
        if (($xmldb_field->getType() == XMLDB_TYPE_INTEGER) ||