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--- jdatabase [2010/09/27 14:29]
10.12.12.87
+++ jdatabase [2017/03/27 17:44] (actual)
@@ Línea 1: / Línea 1: @@
-{{ambox|type=merge|image=merge|text=It has been suggested that this page or section be merged with [[Tutorial:How to use the database classes in your script]]. ([[Talk:How to use the database classes in your script|Discuss here]])}}
 Joomla provides a sophisticated database abstraction layer to simplify the usage for third party developers. This guide will help you use this layer.
-==Why should I use the Joomla database class?==
+=== Why should I use the Joomla database class? ===
 Joomla can use different kinds of SQL database systems and run in a variety of environments with different table-prefixes. In addition to these functions, the class automatically creates the database connection. Besides instantiating the object you need just two lines of code to get a result from the database in a variety of formats. Using the Joomla database layer ensures a maximum of compatibility and flexibility for your extension.
-==Preparing the query==
+=== Preparing the query ===
-<code lang="php">
+<PHP>
 // Get a database object
 $db =& JFactory::getDBO();
@@ Línea 12: / Línea 11: @@
 $query = "SELECT * FROM #__example_table WHERE id = 999999;";
 $db->setQuery($query);
-</code>
+</PHP>
-First we instantiate the database object; then we prepare the query. You can use the normal SQL syntax. The only thing you have to change is the table prefix. To make this as flexible as possible, Joomla uses a placeholder for the prefix, the &ldquo;#__&rdquo;. In the next step, the $db->setQuery(), this string is replaced with the correct prefix.
+First we instantiate the database object; then we prepare the query. You can use the normal SQL syntax. The only thing you have to change is the table prefix. To make this as flexible as possible, Joomla uses a placeholder for the prefix, the "#_". In the next step, the $db->setQuery(), this string is replaced with the correct prefix.
-Now, if we don't want to get information from the database, but rather insert a row into it, we need one more function. Every string value in the SQL syntax should be quoted. For example, MySQL uses backticks &#096;&#096; for names and single quotes &lsquo;&lsquo; for values. Joomla has some functions to do this for us and to ensure code compatibility between different databases. We can pass the names to the function $db->nameQuote($name) and the values to the function $db->Quote($value).
+Now, if we don't want to get information from the database, but rather insert a row into it, we need one more function. Every string value in the SQL syntax should be quoted. For example, MySQL uses backticks `` for names and single quotes ‘‘ for values. Joomla has some functions to do this for us and to ensure code compatibility between different databases. We can pass the names to the function $db->nameQuote($name) and the values to the function $db->Quote($value).
 A fully quoted query example is:
-<source lang="php">
+<PHP>
 $query = "
   SELECT *
@@ Línea 25: / Línea 24: @@
     WHERE ".$db->nameQuote('id')." = ".$db->quote('999999').";
   ";
-</source>
+</PHP>
 Whatever we want to do, we have to set the query with the $db->setQuery() function. Although you could write the query directly as a parameter for $db->setQuery(), it's commonly done by first saving it in a variable, normally $query, and then handing this variable over. This results in clean, readable code.
@@ Línea 31: / Línea 30: @@
 ==== setQuery($query) ====
 The ''setQuery($query)'' method sets up a database query for later execution either by the query() method or one of the Load result methods.
-<source lang="php">
+<PHP>
 $db =& JFactory::getDBO();
 $query = "/* some valid sql string */";
 $db->setQuery($query);
-</source>
+</PHP>
 Notes:
@@ Línea 42: / Línea 41: @@
 setQuery() also takes three other parameters: $offset, $limit (both used in list pagination) and $prefix, an alternative table prefix. All three variables have default values set and can usually be ignored.
-==Executing the Query==
+=== Executing the Query ===
 To execute the query, Joomla provides several functions, which differ in their return value.
-=== Basic Query Execution ===
+==== Basic Query Execution ====
-==== query() ====
+===== query() =====
 The ''query()'' method is the the basic tool for executing SQL queries on a database. In Joomla it is most often used for updating or administering the database simply because the various load methods detailed on this page have the query step built into them.
-The syntax is very straightforward:<source lang="php">$db =& JFactory::getDBO();
+The syntax is very straightforward:<PHP>$db =& JFactory::getDBO();
 $query = "/* some valid sql string */";
 $db->setQuery($query);
-$result = $db->query();</source>
+$result = $db->query();</PHP>
 Note: $query() returns an appropriate database resource if successful, or FALSE if not.
-=== Query Execution Information ===
+==== Query Execution Information ====
 * getAffectedRows()
 * explain()
 * insertid()
-=== Insert Query Execution ===
+==== Insert Query Execution ====
 * insertObject()
-==Query Results ==
+=== Query Results ===
 The database class contains many methods for working with a query's result set.
-=== Single Value Result ===
+==== Single Value Result ====
-==== loadResult() ====
+===== loadResult() =====
 Use '''loadResult()''' when you expect just a single value back from your database query.
@@ Línea 83: / Línea 82: @@
 This is often the result of a 'count' query to get a number of records:
-<source lang='php'>
+<PHP>
 $db =& JFactory::getDBO();
 $query = "
@@ Línea 92: / Línea 91: @@
 $db->setQuery($query);
 $count = $db->loadResult();
-</source>
+</PHP>
 or where you are just looking for a single field from a single row of the table (or possibly a single field from the first row returned).
-<source lang='php'>
+<PHP>
 $db =& JFactory::getDBO();
 $query = "
@@ Línea 103: / Línea 102: @@
 $db->setQuery($query);
 $result = $db->loadResult();
-</source>
+</PHP>
-===Single Row Results ===
+====Single Row Results ====
 Each of these results functions will return a single record from the database even though there may be several records that meet the criteria that you have set. To get more records you need to call the function again.
 {| class="wikitable" style="text-align:center"
@@ Línea 118: / Línea 117: @@
 |}
-==== loadRow() ====
+===== loadRow() =====
 loadRow() returns an indexed array from a single record in the table:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $row = $db->loadRow();
 print_r($row);
-</source>
+</PHP>
 will give:
-<pre>Array ( [0] => 1 [1] => John Smith [2] => johnsmith@example.com [3] => johnsmith ) </pre>
+<code>Array ( [0] => 1 [1] => John Smith [2] => johnsmith@example.com [3] => johnsmith ) </code>
-You can access the individual values by using:<pre>$row['index'] // e.g. $row['2']</pre>
+You can access the individual values by using:<code>$row['index'] // e.g. $row['2']</code>
 Notes:
@@ Línea 135: / Línea 134: @@
 # Whilst you can repeat the call to get further rows, one of the functions that returns multiple rows might be more useful.
-==== loadAssoc() ====
+===== loadAssoc() =====
 loadAssoc() returns an associated array from a single record in the table:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $row = $db->loadAssoc();
 print_r($row);
-</source>
+</PHP>
 will give:
-<pre>Array ( [id] => 1 [name] => John Smith [email] => johnsmith@example.com [username] => johnsmith )</pre>
+<code>Array ( [id] => 1 [name] => John Smith [email] => johnsmith@example.com [username] => johnsmith )</code>
-You can access the individual values by using:<pre>$row['name'] // e.g. $row['name']</pre>
+You can access the individual values by using:<code>$row['name'] // e.g. $row['name']</code>
 Notes:
 # Whilst you can repeat the call to get further rows, one of the functions that returns multiple rows might be more useful.
-==== loadObject() ====
+===== loadObject() =====
 loadObject returns a PHP object from a single record in the table:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $result = $db->loadObject();
 print_r($result);
-</source>
+</PHP>
 will give:
-<pre>stdClass Object ( [id] => 1 [name] => John Smith [email] => johnsmith@example.com [username] => johnsmith )</pre>
+<code>stdClass Object ( [id] => 1 [name] => John Smith [email] => johnsmith@example.com [username] => johnsmith )</code>
-You can access the individual values by using:<pre>$row->index // e.g. $row->email</pre>
+You can access the individual values by using:<code>$row->index // e.g. $row->email</code>
 Notes:
 # Whilst you can repeat the call to get further rows, one of the functions that returns multiple rows might be more useful.
-===Single Column Results ===
+====Single Column Results ====
 Each of these results functions will return a single column from the database.
@@ Línea 181: / Línea 180: @@
 |}
-==== loadResultArray() ====
+===== loadResultArray() =====
 loadResultArray() returns an indexed array from a single column in the table:
-<source lang='php'>
+<PHP>
 $query = "
   SELECT name, email, username
@@ Línea 191: / Línea 190: @@
 $column= $db->loadResultArray();
 print_r($column);
-</source>
+</PHP>
 will give:
-<pre>Array ( [0] => John Smith [1] => Magda Hellman [2] => Yvonne de Gaulle )</pre>
+<code>Array ( [0] => John Smith [1] => Magda Hellman [2] => Yvonne de Gaulle )</code>
-You can access the individual values by using:<pre>$column['index'] // e.g. $column['2']</pre>
+You can access the individual values by using:<code>$column['index'] // e.g. $column['2']</code>
 Notes:
@@ Línea 201: / Línea 200: @@
 # loadResultArray() is equivalent to loadResultArray(0).
-==== loadResultArray($index) ====
+===== loadResultArray($index) =====
 loadResultArray($index) returns an indexed array from a single column in the table:
-<source lang='php'>
+<PHP>
 $query = "
   SELECT name, email, username
@@ Línea 211: / Línea 210: @@
 $column= $db->loadResultArray(1);
 print_r($column);
-</source>
+</PHP>
 will give:
-<pre>Array ( [0] => johnsmith@example.com [1] => magda_h@example.com [2] => ydg@example.com )</pre>
+<code>Array ( [0] => johnsmith@example.com [1] => magda_h@example.com [2] => ydg@example.com )</code>
-You can access the individual values by using:<pre>$column['index'] // e.g. $column['2']</pre>
+You can access the individual values by using:<code>$column['index'] // e.g. $column['2']</code>
 loadResultArray($index) allows you to iterate through a series of columns in the results
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
@@ Línea 225: / Línea 224: @@
   print_r($column);
 }
-</source>
+</PHP>
 will give:
-<pre>Array ( [0] => John Smith [1] => Magda Hellman [2] => Yvonne de Gaulle )
+<code>Array ( [0] => John Smith [1] => Magda Hellman [2] => Yvonne de Gaulle )
 Array ( [0] => johnsmith@example.com [1] => magda_h@example.com [2] => ydg@example.com )
-Array ( [0] => johnsmith [1] => magdah [2] => ydegaulle )</pre>
+Array ( [0] => johnsmith [1] => magdah [2] => ydegaulle )</code>
-</pre>
+</code>
 Notes:
 # The array indices are numeric starting from zero.
-=== Multi-Row Results ===
+==== Multi-Row Results ====
 Each of these results functions will return multiple records from the database.
@@ Línea 249: / Línea 248: @@
 |}
-==== loadRowList() ====
+===== loadRowList() =====
 loadRowList() returns an indexed array of indexed arrays from the table records returned by the query:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $row = $db->loadRowList();
 print_r($row);
-</source>
+</PHP>
 will give (with line breaks added for clarity):
-<pre>Array (
+<code>Array (
 [0] => Array ( [0] => 1 [1] => John Smith [2] => johnsmith@example.com [3] => johnsmith )
 [1] => Array ( [0] => 2 [1] => Magda Hellman [2] => magda_h@example.com [3] => magdah )
 [2] => Array ( [0] => 3 [1] => Yvonne de Gaulle [2] => ydg@example.com [3] => ydegaulle )
-)</pre>
+)</code>
-You can access the individual rows by using:<pre>$row['index'] // e.g. $row['2']</pre>
+You can access the individual rows by using:<code>$row['index'] // e.g. $row['2']</code>
-and you can access the individual values by using:<pre>$row['index']['index'] // e.g. $row['2']['3']</pre>
+and you can access the individual values by using:<code>$row['index']['index'] // e.g. $row['2']['3']</code>
 Notes:
 # The array indices are numeric starting from zero.
-==== loadAssocList() ====
+===== loadAssocList() =====
 loadAssocList() returns an indexed array of associated arrays from the table records returned by the query:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $row = $db->loadAssocList();
 print_r($row);
-</source>
+</PHP>
 will give (with line breaks added for clarity):
-<pre>Array (
+<code>Array (
 [0] => Array ( [id] => 1 [name] => John Smith [email] => johnsmith@example.com [username] => johnsmith )
 [1] => Array ( [id] => 2 [name] => Magda Hellman [email] => magda_h@example.com [username] => magdah )
 [2] => Array ( [id] => 3 [name] => Yvonne de Gaulle [email] => ydg@example.com [username] => ydegaulle )
-) </pre>
+) </code>
-You can access the individual rows by using:<pre>$row['index'] // e.g. $row['2']</pre>
+You can access the individual rows by using:<code>$row['index'] // e.g. $row['2']</code>
-and you can access the individual values by using:<pre>$row['index']['column_name'] // e.g. $row['2']['email']</pre>
+and you can access the individual values by using:<code>$row['index']['column_name'] // e.g. $row['2']['email']</code>
-==== loadAssocList($key) ====
+===== loadAssocList($key) =====
 loadAssocList('key') returns an associated array - indexed on 'key' - of associated arrays from the table records returned by the query:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $row = $db->loadAssocList('username');
 print_r($row);
-</source>
+</PHP>
 will give (with line breaks added for clarity):
-<pre>Array (
+<code>Array (
 [johnsmith] => Array ( [id] => 1 [name] => John Smith [email] => johnsmith@example.com [username] => johnsmith )
 [magdah] => Array ( [id] => 2 [name] => Magda Hellman [email] => magda_h@example.com [username] => magdah )
 [ydegaulle] => Array ( [id] => 3 [name] => Yvonne de Gaulle [email] => ydg@example.com [username] => ydegaulle )
-)</pre>
+)</code>
-You can access the individual rows by using:<pre>$row['key_value'] // e.g. $row['johnsmith']</pre>
+You can access the individual rows by using:<code>$row['key_value'] // e.g. $row['johnsmith']</code>
-and you can access the individual values by using:<pre>$row['key_value']['column_name'] // e.g. $row['johnsmith']['email']</pre>
+and you can access the individual values by using:<code>$row['key_value']['column_name'] // e.g. $row['johnsmith']['email']</code>
 Note: Key must be a valid column name from the table; it does not have to be an Index or a Primary Key. But if it does not have a unique value you may not be able to retrieve results reliably.
-==== loadObjectList() ====
+===== loadObjectList() =====
 loadObjectList() returns an indexed array of PHP objects from the table records returned by the query:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $result = $db->loadObjectList();
 print_r($result);
-</source>
+</PHP>
 will give (with line breaks added for clarity):
-<pre>Array (
+<code>Array (
 [0] => stdClass Object ( [id] => 1 [name] => John Smith
     [email] => johnsmith@example.com [username] => johnsmith )
@@ Línea 324: / Línea 323: @@
 [2] => stdClass Object ( [id] => 3 [name] => Yvonne de Gaulle
     [email] => ydg@example.com [username] => ydegaulle )
-)</pre>
+)</code>
-You can access the individual rows by using:<pre>$row['index'] // e.g. $row['2']</pre>
+You can access the individual rows by using:<code>$row['index'] // e.g. $row['2']</code>
-and you can access the individual values by using:<pre>$row['index']->name // e.g. $row['2']->email</pre>
+and you can access the individual values by using:<code>$row['index']->name // e.g. $row['2']->email</code>
-==== loadObjectList('key') ====
+===== loadObjectList('key') =====
 loadObjectList($key) returns an associated array - indexed on 'key' - of objects from the table records returned by the query:
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
 $row = $db->loadObjectList('username');
 print_r($row);
-</source>
+</PHP>
 will give (with line breaks added for clarity):
-<pre>Array (
+<code>Array (
 [johnsmith] => stdClass Object ( [id] => 1 [name] => John Smith
     [email] => johnsmith@example.com [username] => johnsmith )
@@ Línea 345: / Línea 344: @@
 [ydegaulle] => stdClass Object ( [id] => 3 [name] => Yvonne de Gaulle
     [email] => ydg@example.com [username] => ydegaulle )
-)</pre>
+)
+</code>
-You can access the individual rows by using:<pre>$row['key_value'] // e.g. $row['johnsmith']</pre>
+You can access the individual rows by using:<code>$row['key_value'] // e.g. $row['johnsmith']</code>
-and you can access the individual values by using:<pre>$row['key_value']->column_name // e.g. $row['johnsmith']->email</pre>
+and you can access the individual values by using:<code>$row['key_value']->column_name // e.g. $row['johnsmith']->email</code>
 Note: Key must be a valid column name from the table; it does not have to be an Index or a Primary Key. But if it does not have a unique value you may not be able to retrieve results reliably.
-=== Miscellaneous Result Set Methods ===
+==== Miscellaneous Result Set Methods ====
-==== getNumRows() ====
+===== getNumRows() =====
 getNumRows() will return the number of result rows found by the last query and waiting to be read. To get a result from getNumRows() you have to run it '''after''' the query and '''before''' you have retrieved any results.
-<source lang='php'>
+<PHP>
 . . .
 $db->setQuery($query);
@@ Línea 362: / Línea 362: @@
 print_r($num_rows);
 $result = $db->loadRowList();
-</source>
+</PHP>
-will return <pre>3</pre>
+will return <code>3</code>
 Note: if you run getNumRows() after loadRowList() - or any other retrieval method - you may get a PHP Warning:
-<pre>Warning: mysql_num_rows(): 80 is not a valid MySQL result resource
+<code>Warning: mysql_num_rows(): 80 is not a valid MySQL result resource
-in D:\xampp\htdocs\joomla1.5a\libraries\joomla\database\database\mysql.php on line 344</pre>
+in D:\xampp\htdocs\joomla1.5a\libraries\joomla\database\database\mysql.php on line 344</code>
-==Tips, Tricks & FAQ==
+=== Tips, Tricks & FAQ ===
-===Subqueries===
+==== Subqueries ====
 We had a few people lately using subqueries like these:
-<source lang="SQL">
+<PHP>
 SELECT * FROM #__example WHERE id IN (SELECT id FROM #__example2);
-</source>
+</PHP>
 These kinds of queries are only possible in MySQL 4.1 and above. Another way to achieve this, is splitting the query into two:
-<source lang="php">
+<PHP>
 $query = "SELECT id FROM #__example2";
 $database->setQuery($query);
 $query = "SELECT * FROM #__example WHERE id IN (". implode(",", $database->loadResultArray()) .")";
-</source>
+</PHP>
-===Developer-Friendly Tips===
+==== Developer-Friendly Tips ====
 Here is a quick way to do four developer-friendly things at once:
 * Use a simple constant as an SQL seperator (which can probably be used in many queries).
@@ Línea 386: / Línea 386: @@
 * Give an error inside your (component-) content without really setting debugging on.
 * Have a visibly nice SQL by splitting SQL groups with linebreaks in your error.
-<source lang="php">
+<PHP>
 $db =& JFactory::getDBO();
 $jAp=& JFactory::getApplication();
@@ Línea 400: / Línea 400: @@
     //display and convert to HTML when SQL error
 if (is_null($posts=$db->loadRowList())) {$jAp->enqueueMessage(nl2br($db->getErrorMsg()),'error'); return;}
-</source>
+</PHP>
-<noinclude>[[Category:Development]][[Category:Database]]</noinclude>
+[[Category:Development]][[Category:Database]]