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/wp-admin/ -> install-helper.php (source)

   1  <?php
   2  /**
   3   * Plugins may load this file to gain access to special helper functions for
   4   * plugin installation. This file is not included by WordPress and it is
   5   * recommended, to prevent fatal errors, that this file is included using
   6   * require_once().
   7   *
   8   * These functions are not optimized for speed, but they should only be used
   9   * once in a while, so speed shouldn't be a concern. If it is and you are
  10   * needing to use these functions a lot, you might experience time outs. If you
  11   * do, then it is advised to just write the SQL code yourself.
  12   *
  13   *     check_column( 'wp_links', 'link_description', 'mediumtext' );
  14   *     if ( check_column( $wpdb->comments, 'comment_author', 'tinytext' ) ) {
  15   *         echo "ok\n";
  16   *     }
  17   *
  18   *     $error_count = 0;
  19   *     $tablename = $wpdb->links;
  20   *     // Check the column.
  21   *     if ( ! check_column($wpdb->links, 'link_description', 'varchar( 255 )' ) ) {
  22   *         $ddl = "ALTER TABLE $wpdb->links MODIFY COLUMN link_description varchar(255) NOT NULL DEFAULT '' ";
  23   *         $q = $wpdb->query( $ddl );
  24   *     }
  25   *
  26   *     if ( check_column( $wpdb->links, 'link_description', 'varchar( 255 )' ) ) {
  27   *         $res .= $tablename . ' - ok <br />';
  28   *     } else {
  29   *         $res .= 'There was a problem with ' . $tablename . '<br />';
  30   *         ++$error_count;
  31   *     }
  32   *
  33   * @package WordPress
  34   * @subpackage Plugin
  35   */
  36  
  37  /** Load WordPress Bootstrap */
  38  require_once( dirname( dirname( __FILE__ ) ) . '/wp-load.php' );
  39  
  40  if ( ! function_exists( 'maybe_create_table' ) ) :
  41      /**
  42       * Create database table, if it doesn't already exist.
  43       *
  44       * @since 1.0.0
  45       *
  46       * @global wpdb $wpdb WordPress database abstraction object.
  47       *
  48       * @param string $table_name Database table name.
  49       * @param string $create_ddl Create database table SQL.
  50       * @return bool False on error, true if already exists or success.
  51       */
  52  	function maybe_create_table( $table_name, $create_ddl ) {
  53          global $wpdb;
  54          foreach ( $wpdb->get_col( 'SHOW TABLES', 0 ) as $table ) {
  55              if ( $table == $table_name ) {
  56                  return true;
  57              }
  58          }
  59          // Didn't find it, so try to create it.
  60          $wpdb->query( $create_ddl );
  61  
  62          // We cannot directly tell that whether this succeeded!
  63          foreach ( $wpdb->get_col( 'SHOW TABLES', 0 ) as $table ) {
  64              if ( $table == $table_name ) {
  65                  return true;
  66              }
  67          }
  68          return false;
  69      }
  70  endif;
  71  
  72  if ( ! function_exists( 'maybe_add_column' ) ) :
  73      /**
  74       * Add column to database table, if column doesn't already exist in table.
  75       *
  76       * @since 1.0.0
  77       *
  78       * @global wpdb $wpdb WordPress database abstraction object.
  79       *
  80       * @param string $table_name Database table name
  81       * @param string $column_name Table column name
  82       * @param string $create_ddl SQL to add column to table.
  83       * @return bool False on failure. True, if already exists or was successful.
  84       */
  85  	function maybe_add_column( $table_name, $column_name, $create_ddl ) {
  86          global $wpdb;
  87          foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
  88  
  89              if ( $column == $column_name ) {
  90                  return true;
  91              }
  92          }
  93  
  94          // Didn't find it, so try to create it.
  95          $wpdb->query( $create_ddl );
  96  
  97          // We cannot directly tell that whether this succeeded!
  98          foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
  99              if ( $column == $column_name ) {
 100                  return true;
 101              }
 102          }
 103          return false;
 104      }
 105  endif;
 106  
 107  /**
 108   * Drop column from database table, if it exists.
 109   *
 110   * @since 1.0.0
 111   *
 112   * @global wpdb $wpdb WordPress database abstraction object.
 113   *
 114   * @param string $table_name Table name
 115   * @param string $column_name Column name
 116   * @param string $drop_ddl SQL statement to drop column.
 117   * @return bool False on failure, true on success or doesn't exist.
 118   */
 119  function maybe_drop_column( $table_name, $column_name, $drop_ddl ) {
 120      global $wpdb;
 121      foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
 122          if ( $column == $column_name ) {
 123  
 124              // Found it, so try to drop it.
 125              $wpdb->query( $drop_ddl );
 126  
 127              // We cannot directly tell that whether this succeeded!
 128              foreach ( $wpdb->get_col( "DESC $table_name", 0 ) as $column ) {
 129                  if ( $column == $column_name ) {
 130                      return false;
 131                  }
 132              }
 133          }
 134      }
 135      // Else didn't find it.
 136      return true;
 137  }
 138  
 139  /**
 140   * Check column matches criteria.
 141   *
 142   * Uses the SQL DESC for retrieving the table info for the column. It will help
 143   * understand the parameters, if you do more research on what column information
 144   * is returned by the SQL statement. Pass in null to skip checking that
 145   * criteria.
 146   *
 147   * Column names returned from DESC table are case sensitive and are listed:
 148   *      Field
 149   *      Type
 150   *      Null
 151   *      Key
 152   *      Default
 153   *      Extra
 154   *
 155   * @since 1.0.0
 156   *
 157   * @global wpdb $wpdb WordPress database abstraction object.
 158   *
 159   * @param string $table_name Table name
 160   * @param string $col_name   Column name
 161   * @param string $col_type   Column type
 162   * @param bool   $is_null    Optional. Check is null.
 163   * @param mixed  $key        Optional. Key info.
 164   * @param mixed  $default    Optional. Default value.
 165   * @param mixed  $extra      Optional. Extra value.
 166   * @return bool True, if matches. False, if not matching.
 167   */
 168  function check_column( $table_name, $col_name, $col_type, $is_null = null, $key = null, $default = null, $extra = null ) {
 169      global $wpdb;
 170      $diffs   = 0;
 171      $results = $wpdb->get_results( "DESC $table_name" );
 172  
 173      foreach ( $results as $row ) {
 174  
 175          if ( $row->Field == $col_name ) {
 176  
 177              // Got our column, check the params.
 178              if ( ( $col_type != null ) && ( $row->Type != $col_type ) ) {
 179                  ++$diffs;
 180              }
 181              if ( ( $is_null != null ) && ( $row->Null != $is_null ) ) {
 182                  ++$diffs;
 183              }
 184              if ( ( $key != null ) && ( $row->Key != $key ) ) {
 185                  ++$diffs;
 186              }
 187              if ( ( $default != null ) && ( $row->Default != $default ) ) {
 188                  ++$diffs;
 189              }
 190              if ( ( $extra != null ) && ( $row->Extra != $extra ) ) {
 191                  ++$diffs;
 192              }
 193              if ( $diffs > 0 ) {
 194                  return false;
 195              }
 196              return true;
 197          } // end if found our column
 198      }
 199      return false;
 200  }


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