[Summary view] [Print] [Text view]

   1  <?php
   2  
   3  /**
   4   * @file
   5   * Database interface code for PostgreSQL database servers.
   6   */
   7  
   8  /**
   9   * @ingroup database
  10   * @{
  11   */
  12  
  13  /**
  14   * Report database status.
  15   */
  16  function db_status_report() {
  17    $t = get_t();
  18  
  19    $version = db_version();
  20  
  21    $form['pgsql'] = array(
  22      'title' => $t('PostgreSQL database'),
  23      'value' => $version,
  24    );
  25  
  26    if (version_compare($version, DRUPAL_MINIMUM_PGSQL) < 0) {
  27      $form['pgsql']['severity'] = REQUIREMENT_ERROR;
  28      $form['pgsql']['description'] = $t('Your PostgreSQL Server is too old. Drupal requires at least PostgreSQL %version.', array('%version' => DRUPAL_MINIMUM_PGSQL));
  29    }
  30  
  31    return $form;
  32  }
  33  
  34  /**
  35   * Returns the version of the database server currently in use.
  36   *
  37   * @return Database server version
  38   */
  39  function db_version() {
  40    return db_result(db_query("SHOW SERVER_VERSION"));
  41  }
  42  
  43  /**
  44   * Initialize a database connection.
  45   */
  46  function db_connect($url) {
  47    // Check if PostgreSQL support is present in PHP
  48    if (!function_exists('pg_connect')) {
  49      _db_error_page('Unable to use the PostgreSQL database because the PostgreSQL extension for PHP is not installed. Check your <code>php.ini</code> to see how you can enable it.');
  50    }
  51  
  52    $url = parse_url($url);
  53    $conn_string = '';
  54  
  55    // Decode url-encoded information in the db connection string
  56    if (isset($url['user'])) {
  57      $conn_string .= ' user='. urldecode($url['user']);
  58    }
  59    if (isset($url['pass'])) {
  60      $conn_string .= ' password='. urldecode($url['pass']);
  61    }
  62    if (isset($url['host'])) {
  63      $conn_string .= ' host='. urldecode($url['host']);
  64    }
  65    if (isset($url['path'])) {
  66      $conn_string .= ' dbname='. substr(urldecode($url['path']), 1);
  67    }
  68    if (isset($url['port'])) {
  69      $conn_string .= ' port='. urldecode($url['port']);
  70    }
  71  
  72    // pg_last_error() does not return a useful error message for database
  73    // connection errors. We must turn on error tracking to get at a good error
  74    // message, which will be stored in $php_errormsg.
  75    $track_errors_previous = ini_get('track_errors');
  76    ini_set('track_errors', 1);
  77  
  78    $connection = @pg_connect($conn_string);
  79    if (!$connection) {
  80      require_once  './includes/unicode.inc';
  81      _db_error_page(decode_entities($php_errormsg));
  82    }
  83  
  84    // Restore error tracking setting
  85    ini_set('track_errors', $track_errors_previous);
  86  
  87    pg_query($connection, "set client_encoding=\"UTF8\"");
  88    return $connection;
  89  }
  90  
  91  /**
  92   * Runs a basic query in the active database.
  93   *
  94   * User-supplied arguments to the query should be passed in as separate
  95   * parameters so that they can be properly escaped to avoid SQL injection
  96   * attacks.
  97   *
  98   * @param $query
  99   *   A string containing an SQL query.
 100   * @param ...
 101   *   A variable number of arguments which are substituted into the query
 102   *   using printf() syntax. Instead of a variable number of query arguments,
 103   *   you may also pass a single array containing the query arguments.
 104   *
 105   *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
 106   *   in '') and %%.
 107   *
 108   *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
 109   *   and TRUE values to decimal 1.
 110   *
 111   * @return
 112   *   A database query result resource, or FALSE if the query was not
 113   *   executed correctly.
 114   */
 115  function db_query($query) {
 116    $args = func_get_args();
 117    array_shift($args);
 118    $query = db_prefix_tables($query);
 119    if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
 120      $args = $args[0];
 121    }
 122    _db_query_callback($args, TRUE);
 123    $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
 124    return _db_query($query);
 125  }
 126  
 127  /**
 128   * Helper function for db_query().
 129   */
 130  function _db_query($query, $debug = 0) {
 131    global $active_db, $last_result, $queries;
 132  
 133    if (variable_get('dev_query', 0)) {
 134      list($usec, $sec) = explode(' ', microtime());
 135      $timer = (float)$usec + (float)$sec;
 136    }
 137  
 138    $last_result = pg_query($active_db, $query);
 139  
 140    if (variable_get('dev_query', 0)) {
 141      $bt = debug_backtrace();
 142      $query = $bt[2]['function'] ."\n". $query;
 143      list($usec, $sec) = explode(' ', microtime());
 144      $stop = (float)$usec + (float)$sec;
 145      $diff = $stop - $timer;
 146      $queries[] = array($query, $diff);
 147    }
 148  
 149    if ($debug) {
 150      print '<p>query: '. $query .'<br />error:'. pg_last_error($active_db) .'</p>';
 151    }
 152  
 153    if ($last_result !== FALSE) {
 154      return $last_result;
 155    }
 156    else {
 157      // Indicate to drupal_error_handler that this is a database error.
 158      $DB_ERROR} = TRUE;
 159      trigger_error(check_plain(pg_last_error($active_db) ."\nquery: ". $query), E_USER_WARNING);
 160      return FALSE;
 161    }
 162  }
 163  
 164  /**
 165   * Fetch one result row from the previous query as an object.
 166   *
 167   * @param $result
 168   *   A database query result resource, as returned from db_query().
 169   * @return
 170   *   An object representing the next row of the result, or FALSE. The attributes
 171   *   of this object are the table fields selected by the query.
 172   */
 173  function db_fetch_object($result) {
 174    if ($result) {
 175      return pg_fetch_object($result);
 176    }
 177  }
 178  
 179  /**
 180   * Fetch one result row from the previous query as an array.
 181   *
 182   * @param $result
 183   *   A database query result resource, as returned from db_query().
 184   * @return
 185   *   An associative array representing the next row of the result, or FALSE.
 186   *   The keys of this object are the names of the table fields selected by the
 187   *   query, and the values are the field values for this result row.
 188   */
 189  function db_fetch_array($result) {
 190    if ($result) {
 191      return pg_fetch_assoc($result);
 192    }
 193  }
 194  
 195  /**
 196   * Return an individual result field from the previous query.
 197   *
 198   * Only use this function if exactly one field is being selected; otherwise,
 199   * use db_fetch_object() or db_fetch_array().
 200   *
 201   * @param $result
 202   *   A database query result resource, as returned from db_query().
 203   * @return
 204   *   The resulting field or FALSE.
 205   */
 206  function db_result($result) {
 207    if ($result && pg_num_rows($result) > 0) {
 208      $array = pg_fetch_row($result);
 209      return $array[0];
 210    }
 211    return FALSE;
 212  }
 213  
 214  /**
 215   * Determine whether the previous query caused an error.
 216   */
 217  function db_error() {
 218    global $active_db;
 219    return pg_last_error($active_db);
 220  }
 221  
 222  /**
 223   * Returns the last insert id. This function is thread safe.
 224   *
 225   * @param $table
 226   *   The name of the table you inserted into.
 227   * @param $field
 228   *   The name of the autoincrement field.
 229   */
 230  function db_last_insert_id($table, $field) {
 231    return db_result(db_query("SELECT CURRVAL('{". db_escape_table($table) ."}_". db_escape_table($field) ."_seq')"));
 232  }
 233  
 234  /**
 235   * Determine the number of rows changed by the preceding query.
 236   */
 237  function db_affected_rows() {
 238    global $last_result;
 239    return empty($last_result) ? 0 : pg_affected_rows($last_result);
 240  }
 241  
 242  /**
 243   * Runs a limited-range query in the active database.
 244   *
 245   * Use this as a substitute for db_query() when a subset of the query
 246   * is to be returned.
 247   * User-supplied arguments to the query should be passed in as separate
 248   * parameters so that they can be properly escaped to avoid SQL injection
 249   * attacks.
 250   *
 251   * @param $query
 252   *   A string containing an SQL query.
 253   * @param ...
 254   *   A variable number of arguments which are substituted into the query
 255   *   using printf() syntax. Instead of a variable number of query arguments,
 256   *   you may also pass a single array containing the query arguments.
 257   *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
 258   *   in '') and %%.
 259   *
 260   *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
 261   *   and TRUE values to decimal 1.
 262   *
 263   * @param $from
 264   *   The first result row to return.
 265   * @param $count
 266   *   The maximum number of result rows to return.
 267   * @return
 268   *   A database query result resource, or FALSE if the query was not executed
 269   *   correctly.
 270   */
 271  function db_query_range($query) {
 272    $args = func_get_args();
 273    $count = array_pop($args);
 274    $from = array_pop($args);
 275    array_shift($args);
 276  
 277    $query = db_prefix_tables($query);
 278    if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
 279      $args = $args[0];
 280    }
 281    _db_query_callback($args, TRUE);
 282    $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
 283    $query .= ' LIMIT '. (int)$count .' OFFSET '. (int)$from;
 284    return _db_query($query);
 285  }
 286  
 287  /**
 288   * Runs a SELECT query and stores its results in a temporary table.
 289   *
 290   * Use this as a substitute for db_query() when the results need to stored
 291   * in a temporary table. Temporary tables exist for the duration of the page
 292   * request.
 293   * User-supplied arguments to the query should be passed in as separate parameters
 294   * so that they can be properly escaped to avoid SQL injection attacks.
 295   *
 296   * Note that if you need to know how many results were returned, you should do
 297   * a SELECT COUNT(*) on the temporary table afterwards. db_affected_rows() does
 298   * not give consistent result across different database types in this case.
 299   *
 300   * @param $query
 301   *   A string containing a normal SELECT SQL query.
 302   * @param ...
 303   *   A variable number of arguments which are substituted into the query
 304   *   using printf() syntax. The query arguments can be enclosed in one
 305   *   array instead.
 306   *   Valid %-modifiers are: %s, %d, %f, %b (binary data, do not enclose
 307   *   in '') and %%.
 308   *
 309   *   NOTE: using this syntax will cast NULL and FALSE values to decimal 0,
 310   *   and TRUE values to decimal 1.
 311   *
 312   * @param $table
 313   *   The name of the temporary table to select into. This name will not be
 314   *   prefixed as there is no risk of collision.
 315   * @return
 316   *   A database query result resource, or FALSE if the query was not executed
 317   *   correctly.
 318   */
 319  function db_query_temporary($query) {
 320    $args = func_get_args();
 321    $tablename = array_pop($args);
 322    array_shift($args);
 323  
 324    $query = preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE '. $tablename .' AS SELECT', db_prefix_tables($query));
 325    if (isset($args[0]) and is_array($args[0])) { // 'All arguments in one array' syntax
 326      $args = $args[0];
 327    }
 328    _db_query_callback($args, TRUE);
 329    $query = preg_replace_callback(DB_QUERY_REGEXP, '_db_query_callback', $query);
 330    return _db_query($query);
 331  }
 332  
 333  /**
 334   * Returns a properly formatted Binary Large OBject value.
 335   * In case of PostgreSQL encodes data for insert into bytea field.
 336   *
 337   * @param $data
 338   *   Data to encode.
 339   * @return
 340   *  Encoded data.
 341   */
 342  function db_encode_blob($data) {
 343    return "'". pg_escape_bytea($data) ."'";
 344  }
 345  
 346  /**
 347   * Returns text from a Binary Large OBject value.
 348   * In case of PostgreSQL decodes data after select from bytea field.
 349   *
 350   * @param $data
 351   *   Data to decode.
 352   * @return
 353   *  Decoded data.
 354   */
 355  function db_decode_blob($data) {
 356    return pg_unescape_bytea($data);
 357  }
 358  
 359  /**
 360   * Prepare user input for use in a database query, preventing SQL injection attacks.
 361   * Note: This function requires PostgreSQL 7.2 or later.
 362   */
 363  function db_escape_string($text) {
 364    return pg_escape_string($text);
 365  }
 366  
 367  /**
 368   * Lock a table.
 369   * This function automatically starts a transaction.
 370   */
 371  function db_lock_table($table) {
 372    db_query('BEGIN; LOCK TABLE {'. db_escape_table($table) .'} IN EXCLUSIVE MODE');
 373  }
 374  
 375  /**
 376   * Unlock all locked tables.
 377   * This function automatically commits a transaction.
 378   */
 379  function db_unlock_tables() {
 380    db_query('COMMIT');
 381  }
 382  
 383  /**
 384   * Check if a table exists.
 385   *
 386   * @param $table
 387   *   The name of the table.
 388   *
 389   * @return
 390   *   TRUE if the table exists, and FALSE if the table does not exist.
 391   */
 392  function db_table_exists($table) {
 393    return (bool) db_result(db_query("SELECT COUNT(*) FROM pg_class WHERE relname = '{". db_escape_table($table) ."}'"));
 394  }
 395  
 396  /**
 397   * Check if a column exists in the given table.
 398   *
 399   * @param $table
 400   *   The name of the table.
 401   * @param $column
 402   *   The name of the column.
 403   *
 404   * @return
 405   *   TRUE if the column exists, and FALSE if the column does not exist.
 406   */
 407  function db_column_exists($table, $column) {
 408    return (bool) db_result(db_query("SELECT COUNT(pg_attribute.attname) FROM pg_class, pg_attribute WHERE pg_attribute.attrelid = pg_class.oid AND pg_class.relname = '{". db_escape_table($table) ."}' AND attname = '". db_escape_table($column) ."'"));
 409  }
 410  
 411  /**
 412   * Verify if the database is set up correctly.
 413   */
 414  function db_check_setup() {
 415    $t = get_t();
 416  
 417    $encoding = db_result(db_query('SHOW server_encoding'));
 418    if (!in_array(strtolower($encoding), array('unicode', 'utf8'))) {
 419      drupal_set_message($t('Your PostgreSQL database is set up with the wrong character encoding (%encoding). It is possible it will not work as expected. It is advised to recreate it with UTF-8/Unicode encoding. More information can be found in the <a href="@url">PostgreSQL documentation</a>.', array('%encoding' => $encoding, '@url' => 'http://www.postgresql.org/docs/7.4/interactive/multibyte.html')), 'status');
 420    }
 421  }
 422  
 423  /**
 424   * @} End of "ingroup database".
 425   */
 426  
 427  /**
 428   * @ingroup schemaapi
 429   * @{
 430   */
 431  
 432  /**
 433   * This maps a generic data type in combination with its data size
 434   * to the engine-specific data type.
 435   */
 436  function db_type_map() {
 437    // Put :normal last so it gets preserved by array_flip.  This makes
 438    // it much easier for modules (such as schema.module) to map
 439    // database types back into schema types.
 440    $map = array(
 441      'varchar:normal' => 'varchar',
 442      'char:normal' => 'character',
 443  
 444      'text:tiny' => 'text',
 445      'text:small' => 'text',
 446      'text:medium' => 'text',
 447      'text:big' => 'text',
 448      'text:normal' => 'text',
 449  
 450      'int:tiny' => 'smallint',
 451      'int:small' => 'smallint',
 452      'int:medium' => 'int',
 453      'int:big' => 'bigint',
 454      'int:normal' => 'int',
 455  
 456      'float:tiny' => 'real',
 457      'float:small' => 'real',
 458      'float:medium' => 'real',
 459      'float:big' => 'double precision',
 460      'float:normal' => 'real',
 461  
 462      'numeric:normal' => 'numeric',
 463  
 464      'blob:big' => 'bytea',
 465      'blob:normal' => 'bytea',
 466  
 467      'datetime:normal' => 'timestamp without time zone',
 468  
 469      'serial:tiny' => 'serial',
 470      'serial:small' => 'serial',
 471      'serial:medium' => 'serial',
 472      'serial:big' => 'bigserial',
 473      'serial:normal' => 'serial',
 474    );
 475    return $map;
 476  }
 477  
 478  /**
 479   * Generate SQL to create a new table from a Drupal schema definition.
 480   *
 481   * @param $name
 482   *   The name of the table to create.
 483   * @param $table
 484   *   A Schema API table definition array.
 485   * @return
 486   *   An array of SQL statements to create the table.
 487   */
 488  function db_create_table_sql($name, $table) {
 489    $sql_fields = array();
 490    foreach ($table['fields'] as $field_name => $field) {
 491      $sql_fields[] = _db_create_field_sql($field_name, _db_process_field($field));
 492    }
 493  
 494    $sql_keys = array();
 495    if (isset($table['primary key']) && is_array($table['primary key'])) {
 496      $sql_keys[] = 'PRIMARY KEY ('. implode(', ', $table['primary key']) .')';
 497    }
 498    if (isset($table['unique keys']) && is_array($table['unique keys'])) {
 499      foreach ($table['unique keys'] as $key_name => $key) {
 500        $sql_keys[] = 'CONSTRAINT {'. $name .'}_'. $key_name .'_key UNIQUE ('. implode(', ', $key) .')';
 501      }
 502    }
 503  
 504    $sql = "CREATE TABLE {". $name ."} (\n\t";
 505    $sql .= implode(",\n\t", $sql_fields);
 506    if (count($sql_keys) > 0) {
 507      $sql .= ",\n\t";
 508    }
 509    $sql .= implode(",\n\t", $sql_keys);
 510    $sql .= "\n)";
 511    $statements[] = $sql;
 512  
 513    if (isset($table['indexes']) && is_array($table['indexes'])) {
 514      foreach ($table['indexes'] as $key_name => $key) {
 515        $statements[] = _db_create_index_sql($name, $key_name, $key);
 516      }
 517    }
 518  
 519    return $statements;
 520  }
 521  
 522  function _db_create_index_sql($table, $name, $fields) {
 523    $query = 'CREATE INDEX {'. $table .'}_'. $name .'_idx ON {'. $table .'} (';
 524    $query .= _db_create_key_sql($fields) .')';
 525    return $query;
 526  }
 527  
 528  function _db_create_key_sql($fields) {
 529    $ret = array();
 530    foreach ($fields as $field) {
 531      if (is_array($field)) {
 532        $ret[] = 'substr('. $field[0] .', 1, '. $field[1] .')';
 533      }
 534      else {
 535        $ret[] = $field;
 536      }
 537    }
 538    return implode(', ', $ret);
 539  }
 540  
 541  function _db_create_keys(&$ret, $table, $new_keys) {
 542    if (isset($new_keys['primary key'])) {
 543      db_add_primary_key($ret, $table, $new_keys['primary key']);
 544    }
 545    if (isset($new_keys['unique keys'])) {
 546      foreach ($new_keys['unique keys'] as $name => $fields) {
 547        db_add_unique_key($ret, $table, $name, $fields);
 548      }
 549    }
 550    if (isset($new_keys['indexes'])) {
 551      foreach ($new_keys['indexes'] as $name => $fields) {
 552        db_add_index($ret, $table, $name, $fields);
 553      }
 554    }
 555  }
 556  
 557  /**
 558   * Set database-engine specific properties for a field.
 559   *
 560   * @param $field
 561   *   A field description array, as specified in the schema documentation.
 562   */
 563  function _db_process_field($field) {
 564    if (!isset($field['size'])) {
 565      $field['size'] = 'normal';
 566    }
 567    // Set the correct database-engine specific datatype.
 568    if (!isset($field['pgsql_type'])) {
 569      $map = db_type_map();
 570      $field['pgsql_type'] = $map[$field['type'] .':'. $field['size']];
 571    }
 572    if ($field['type'] == 'serial') {
 573      unset($field['not null']);
 574    }
 575    return $field;
 576  }
 577  
 578  /**
 579   * Create an SQL string for a field to be used in table creation or alteration.
 580   *
 581   * Before passing a field out of a schema definition into this function it has
 582   * to be processed by _db_process_field().
 583   *
 584   * @param $name
 585   *    Name of the field.
 586   * @param $spec
 587   *    The field specification, as per the schema data structure format.
 588   */
 589  function _db_create_field_sql($name, $spec) {
 590    $sql = $name .' '. $spec['pgsql_type'];
 591  
 592    if ($spec['type'] == 'serial') {
 593      unset($spec['not null']);
 594    }
 595  
 596    if (in_array($spec['type'], array('varchar', 'char', 'text')) && isset($spec['length'])) {
 597      $sql .= '('. $spec['length'] .')';
 598    }
 599    elseif (isset($spec['precision']) && isset($spec['scale'])) {
 600      $sql .= '('. $spec['precision'] .', '. $spec['scale'] .')';
 601    }
 602  
 603    if (!empty($spec['unsigned'])) {
 604      $sql .= " CHECK ($name >= 0)";
 605    }
 606  
 607    if (isset($spec['not null']) && $spec['not null']) {
 608      $sql .= ' NOT NULL';
 609    }
 610    if (isset($spec['default'])) {
 611      $default = is_string($spec['default']) ? "'". $spec['default'] ."'" : $spec['default'];
 612      $sql .= " default $default";
 613    }
 614  
 615    return $sql;
 616  }
 617  
 618  /**
 619   * Rename a table.
 620   *
 621   * @param $ret
 622   *   Array to which query results will be added.
 623   * @param $table
 624   *   The table to be renamed.
 625   * @param $new_name
 626   *   The new name for the table.
 627   */
 628  function db_rename_table(&$ret, $table, $new_name) {
 629    $ret[] = update_sql('ALTER TABLE {'. $table .'} RENAME TO {'. $new_name .'}');
 630  }
 631  
 632  /**
 633   * Drop a table.
 634   *
 635   * @param $ret
 636   *   Array to which query results will be added.
 637   * @param $table
 638   *   The table to be dropped.
 639   */
 640  function db_drop_table(&$ret, $table) {
 641    $ret[] = update_sql('DROP TABLE {'. $table .'}');
 642  }
 643  
 644  /**
 645   * Add a new field to a table.
 646   *
 647   * @param $ret
 648   *   Array to which query results will be added.
 649   * @param $table
 650   *   Name of the table to be altered.
 651   * @param $field
 652   *   Name of the field to be added.
 653   * @param $spec
 654   *   The field specification array, as taken from a schema definition.
 655   *   The specification may also contain the key 'initial', the newly
 656   *   created field will be set to the value of the key in all rows.
 657   *   This is most useful for creating NOT NULL columns with no default
 658   *   value in existing tables.
 659   * @param $new_keys
 660   *   Optional keys and indexes specification to be created on the
 661   *   table along with adding the field. The format is the same as a
 662   *   table specification but without the 'fields' element.  If you are
 663   *   adding a type 'serial' field, you MUST specify at least one key
 664   *   or index including it in this array. See db_change_field() for more
 665   *   explanation why.
 666   */
 667  function db_add_field(&$ret, $table, $field, $spec, $new_keys = array()) {
 668    $fixnull = FALSE;
 669    if (!empty($spec['not null']) && !isset($spec['default'])) {
 670      $fixnull = TRUE;
 671      $spec['not null'] = FALSE;
 672    }
 673    $query = 'ALTER TABLE {'. $table .'} ADD COLUMN ';
 674    $query .= _db_create_field_sql($field, _db_process_field($spec));
 675    $ret[] = update_sql($query);
 676    if (isset($spec['initial'])) {
 677      // All this because update_sql does not support %-placeholders.
 678      $sql = 'UPDATE {'. $table .'} SET '. $field .' = '. db_type_placeholder($spec['type']);
 679      $result = db_query($sql, $spec['initial']);
 680      $ret[] = array('success' => $result !== FALSE, 'query' => check_plain($sql .' ('. $spec['initial'] .')'));
 681    }
 682    if ($fixnull) {
 683      $ret[] = update_sql("ALTER TABLE {". $table ."} ALTER $field SET NOT NULL");
 684    }
 685    if (isset($new_keys)) {
 686      _db_create_keys($ret, $table, $new_keys);
 687    }
 688  }
 689  
 690  /**
 691   * Drop a field.
 692   *
 693   * @param $ret
 694   *   Array to which query results will be added.
 695   * @param $table
 696   *   The table to be altered.
 697   * @param $field
 698   *   The field to be dropped.
 699   */
 700  function db_drop_field(&$ret, $table, $field) {
 701    $ret[] = update_sql('ALTER TABLE {'. $table .'} DROP COLUMN '. $field);
 702  }
 703  
 704  /**
 705   * Set the default value for a field.
 706   *
 707   * @param $ret
 708   *   Array to which query results will be added.
 709   * @param $table
 710   *   The table to be altered.
 711   * @param $field
 712   *   The field to be altered.
 713   * @param $default
 714   *   Default value to be set. NULL for 'default NULL'.
 715   */
 716  function db_field_set_default(&$ret, $table, $field, $default) {
 717    if ($default == NULL) {
 718      $default = 'NULL';
 719    }
 720    else {
 721      $default = is_string($default) ? "'$default'" : $default;
 722    }
 723  
 724    $ret[] = update_sql('ALTER TABLE {'. $table .'} ALTER COLUMN '. $field .' SET DEFAULT '. $default);
 725  }
 726  
 727  /**
 728   * Set a field to have no default value.
 729   *
 730   * @param $ret
 731   *   Array to which query results will be added.
 732   * @param $table
 733   *   The table to be altered.
 734   * @param $field
 735   *   The field to be altered.
 736   */
 737  function db_field_set_no_default(&$ret, $table, $field) {
 738    $ret[] = update_sql('ALTER TABLE {'. $table .'} ALTER COLUMN '. $field .' DROP DEFAULT');
 739  }
 740  
 741  /**
 742   * Add a primary key.
 743   *
 744   * @param $ret
 745   *   Array to which query results will be added.
 746   * @param $table
 747   *   The table to be altered.
 748   * @param $fields
 749   *   Fields for the primary key.
 750   */
 751  function db_add_primary_key(&$ret, $table, $fields) {
 752    $ret[] = update_sql('ALTER TABLE {'. $table .'} ADD PRIMARY KEY ('.
 753      implode(',', $fields) .')');
 754  }
 755  
 756  /**
 757   * Drop the primary key.
 758   *
 759   * @param $ret
 760   *   Array to which query results will be added.
 761   * @param $table
 762   *   The table to be altered.
 763   */
 764  function db_drop_primary_key(&$ret, $table) {
 765    $ret[] = update_sql('ALTER TABLE {'. $table .'} DROP CONSTRAINT {'. $table .'}_pkey');
 766  }
 767  
 768  /**
 769   * Add a unique key.
 770   *
 771   * @param $ret
 772   *   Array to which query results will be added.
 773   * @param $table
 774   *   The table to be altered.
 775   * @param $name
 776   *   The name of the key.
 777   * @param $fields
 778   *   An array of field names.
 779   */
 780  function db_add_unique_key(&$ret, $table, $name, $fields) {
 781    $name = '{'. $table .'}_'. $name .'_key';
 782    $ret[] = update_sql('ALTER TABLE {'. $table .'} ADD CONSTRAINT '.
 783      $name .' UNIQUE ('. implode(',', $fields) .')');
 784  }
 785  
 786  /**
 787   * Drop a unique key.
 788   *
 789   * @param $ret
 790   *   Array to which query results will be added.
 791   * @param $table
 792   *   The table to be altered.
 793   * @param $name
 794   *   The name of the key.
 795   */
 796  function db_drop_unique_key(&$ret, $table, $name) {
 797    $name = '{'. $table .'}_'. $name .'_key';
 798    $ret[] = update_sql('ALTER TABLE {'. $table .'} DROP CONSTRAINT '. $name);
 799  }
 800  
 801  /**
 802   * Add an index.
 803   *
 804   * @param $ret
 805   *   Array to which query results will be added.
 806   * @param $table
 807   *   The table to be altered.
 808   * @param $name
 809   *   The name of the index.
 810   * @param $fields
 811   *   An array of field names.
 812   */
 813  function db_add_index(&$ret, $table, $name, $fields) {
 814    $ret[] = update_sql(_db_create_index_sql($table, $name, $fields));
 815  }
 816  
 817  /**
 818   * Drop an index.
 819   *
 820   * @param $ret
 821   *   Array to which query results will be added.
 822   * @param $table
 823   *   The table to be altered.
 824   * @param $name
 825   *   The name of the index.
 826   */
 827  function db_drop_index(&$ret, $table, $name) {
 828    $name = '{'. $table .'}_'. $name .'_idx';
 829    $ret[] = update_sql('DROP INDEX '. $name);
 830  }
 831  
 832  /**
 833   * Change a field definition.
 834   *
 835   * IMPORTANT NOTE: To maintain database portability, you have to explicitly
 836   * recreate all indices and primary keys that are using the changed field.
 837   *
 838   * That means that you have to drop all affected keys and indexes with
 839   * db_drop_{primary_key,unique_key,index}() before calling db_change_field().
 840   * To recreate the keys and indices, pass the key definitions as the
 841   * optional $new_keys argument directly to db_change_field().
 842   *
 843   * For example, suppose you have:
 844   * @code
 845   * $schema['foo'] = array(
 846   *   'fields' => array(
 847   *     'bar' => array('type' => 'int', 'not null' => TRUE)
 848   *   ),
 849   *   'primary key' => array('bar')
 850   * );
 851   * @endcode
 852   * and you want to change foo.bar to be type serial, leaving it as the
 853   * primary key.  The correct sequence is:
 854   * @code
 855   * db_drop_primary_key($ret, 'foo');
 856   * db_change_field($ret, 'foo', 'bar', 'bar',
 857   *   array('type' => 'serial', 'not null' => TRUE),
 858   *   array('primary key' => array('bar')));
 859   * @endcode
 860   *
 861   * The reasons for this are due to the different database engines:
 862   *
 863   * On PostgreSQL, changing a field definition involves adding a new field
 864   * and dropping an old one which* causes any indices, primary keys and
 865   * sequences (from serial-type fields) that use the changed field to be dropped.
 866   *
 867   * On MySQL, all type 'serial' fields must be part of at least one key
 868   * or index as soon as they are created.  You cannot use
 869   * db_add_{primary_key,unique_key,index}() for this purpose because
 870   * the ALTER TABLE command will fail to add the column without a key
 871   * or index specification.  The solution is to use the optional
 872   * $new_keys argument to create the key or index at the same time as
 873   * field.
 874   *
 875   * You could use db_add_{primary_key,unique_key,index}() in all cases
 876   * unless you are converting a field to be type serial. You can use
 877   * the $new_keys argument in all cases.
 878   *
 879   * @param $ret
 880   *   Array to which query results will be added.
 881   * @param $table
 882   *   Name of the table.
 883   * @param $field
 884   *   Name of the field to change.
 885   * @param $field_new
 886   *   New name for the field (set to the same as $field if you don't want to change the name).
 887   * @param $spec
 888   *   The field specification for the new field.
 889   * @param $new_keys
 890   *   Optional keys and indexes specification to be created on the
 891   *   table along with changing the field. The format is the same as a
 892   *   table specification but without the 'fields' element.
 893   */
 894  function db_change_field(&$ret, $table, $field, $field_new, $spec, $new_keys = array()) {
 895    $ret[] = update_sql('ALTER TABLE {'. $table .'} RENAME "'. $field .'" TO "'. $field .'_old"');
 896    $not_null = isset($spec['not null']) ? $spec['not null'] : FALSE;
 897    unset($spec['not null']);
 898  
 899    if (!array_key_exists('size', $spec)) {
 900      $spec['size'] = 'normal';
 901    }
 902    db_add_field($ret, $table, "$field_new", $spec);
 903  
 904    // We need to type cast the new column to best transfer the data
 905    // db_type_map will return possiblities that are not 'cast-able'
 906    // such as serial - they must be made 'int' instead.
 907    $map =  db_type_map();
 908    $typecast = $map[$spec['type'] .':'. $spec['size']];
 909    if (in_array($typecast, array('serial', 'bigserial', 'numeric'))) {
 910      $typecast = 'int';
 911    }
 912    $ret[] = update_sql('UPDATE {'. $table .'} SET '. $field_new .' = CAST('. $field .'_old AS '. $typecast .')');
 913  
 914    if ($not_null) {
 915      $ret[] = update_sql("ALTER TABLE {". $table ."} ALTER $field_new SET NOT NULL");
 916    }
 917  
 918    db_drop_field($ret, $table, $field .'_old');
 919  
 920    if (isset($new_keys)) {
 921      _db_create_keys($ret, $table, $new_keys);
 922    }
 923  }
 924  
 925  /**
 926   * @} End of "ingroup schemaapi".
 927   */
 928