In order to fetch data from a result resource you can use one if the following methods: fetchInto() , fetchOne() . , fetchRow() . , fetchCol() . and fetchAll() . All above mentioned methods except fetchOne() return the requested data encapsuled into a (multi-dimensional-)array, NULL on no more data or a MDB_Error , when an error occurs. All method prefixed with fetch() automatically free the result set.
Example 26-1. Fetching a result set
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The fetch modes supported are:
MDB_FETCHMODE_ORDERED (default)
The fetch*() returns an ordered array. The order is taken from the select statment.
Example 26-2. Fetch a ordered array
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MDB_FETCHMODE_ASSOC
Returns an associative array with the column names as the array keys
Example 26-3. Fetch a assoc. array
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You can set the fetch mode per result call or for your whole MDB instance.
Example 26-4. Per call
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Example 26-5. Once per instance
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The PEAR MDB fetch system also supports an extra parameter to the fetch statement. So you can fetch rows from a result by number. This is especially helpful if you only want to show sets of an entire result (for example in building paginated HTML lists), fetch rows in an special order, etc.
Example 26-6. Fetching by number
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It is recommended to finish the result set after processing in order to to save memory. Use freeResult() to do this.
Example 26-7. Freeing
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MDB provides some special ways to retrieve information from a query without the need of using fetch*() and loop throw results.
queryOne() retrieves the first result of the first column from a query
$numrows = $db->queryOne('select count(id) from clients'); |
queryRow() returns the first row and returns it as an array.
$sql = 'select name, address, phone from clients where id=1'; if (is_array($row = $db->queryRow($sql))) { list($name, $address, $phone) = $row; } |
queryCol() returns an array with the data of the selected column. It accepts the column number to retrieve as the second parameter.
$all_client_names = $db->queryCol('SELECT name FROM clients'); |
$all_client_names = array('Stig', 'Jon', 'Colin'); |
getAll() fetches all the rows returned from a query. This method also has some advanced parameters still will also enable you to return the data as an associative array using the first column as the key.
$data = getAll('SELECT id, text, date FROM mytable'); /* Will return: array( 1 => array('4', 'four', '2004'), 2 => array('5', 'five', '2005'), 3 => array('6', 'six', '2006') ) */ |
The query*() family methods will do all the dirty job for you, this is: launch the query, fetch the data and free the result. Please note that as all PEAR MDB functions they will return a MDB_Error object on errors.
With MDB you have many ways to retrieve useful information from query results. These are:
numRows() : Returns the total number of rows returned from a "SELECT" query.
// Number of rows echo $db->numRows($res); |
numCols() : Returns the total number of columns returned from a "SELECT" query.
// Number of cols echo $db->numCols($res); |
affectedRows() : Returns the number of rows affected by a data manipulation query ("INSERT", "UPDATE" or "DELETE").
// remember that this statement won't return a result object $db->query('DELETE * FROM clients'); echo 'I have deleted ' . $db->affectedRows() . ' clients'; |
tableInfo() : Returns an associative array with information about the returned fields from a "SELECT" query.
// Table Info print_r($db->tableInfo($res)); |