View source for Data manipulation API

{{Template:Migrated|newDocId=/docs/apis/core/dml}}
{{Moodle_2.0}}This page describes the functions available to access data in the Moodle database. You should '''exclusively''' use these functions in order to retrieve or modify database content because these functions provide a high level of abstraction and guarantee that your database manipulation will work against different RDBMSes.

Where possible, tricks and examples will be documented here in order to make developers' lives a bit easier. Of course, feel free to clarify, complete and add more information to this documentation. It will be welcome, absolutely!
== General concepts ==
=== DB object ===
* The data manipulation API is exposed via public methods of the <tt>$DB</tt> object.
* Moodle core takes care of setting up the connection to the database according to values specified in the main config.php file.
* The $DB global object is an instance of the <tt>moodle_database</tt> class. It is instantiated automatically during the bootstrap setup, i.e. as a part of including the main config.php file.
* The DB object is available in the global scope right after including the config.php file:
<syntaxhighlight lang="php">
<?php

require(__DIR__.'/../../../config.php');

// You can access the database via the $DB method calls here.
</syntaxhighlight>
* To make the DB object available in your local scope, such as within a function:
<syntaxhighlight lang="php">
<?php

defined('MOODLE_INTERNAL') || die();

function my_function_making_use_of_database() {
    global $DB;

    // You can access the database via the $DB method calls here.
}
</syntaxhighlight>
=== Table prefix ===
* Most Moodle installations use a prefix for all the database tables, such as <tt>mdl_</tt>. This prefix is NOT to be used in the code in the code itself.
* All the $table parameters in the functions are meant to be the table name without prefixes:
<syntaxhighlight lang="php">$user = $DB->get_record('user', ['id' => '1']);</syntaxhighlight>
* In custom SQL queries, table names must be enclosed between curly braces. They will be then automatically converted to the real prefixed table name. There is no need to access <tt>$CFG->prefix</tt>
<syntaxhighlight lang="php">$user = $DB->get_record_sql('SELECT COUNT(*) FROM {user} WHERE deleted = 1 OR suspended = 1;');</syntaxhighlight>
=== Conditions ===
* All the $conditions parameters in the functions are arrays of fieldname=>fieldvalue elements.
* They all must be fulfilled - i.e. logical <tt>AND</tt> is used to populate the actual <tt>WHERE</tt> statement.
<syntaxhighlight lang="php">$user = $DB->get_record('user', ['firstname' => 'Martin', 'lastname' => 'Dougiamas']);</syntaxhighlight>
=== Placeholders ===
* All the $params parameters in the functions are arrays of values used to fill placeholders in SQL statements.
* Placeholders help to avoid problems with SQL-injection and/or invalid quotes in SQL queries. They facilitate secure and cross-db compatible code.
* Two types of placeholders are supported - question marks (<tt>SQL_PARAMS_QM</tt>) and named placeholders (<tt>SQL_PARAMS_NAMED</tt>).
* Named params '''must be unique''' even if the value passed is the same. If you need to pass the same value multiple times, you need to have multiple distinct named parameters.
<syntaxhighlight lang="php">
// Example of using question mark placeholders.
$DB->get_record_sql('SELECT * FROM {user} WHERE firstname = ? AND lastname = ?', 
    ['Martin', 'Dougiamas']);

// Example of using named placeholders.
$DB->get_record_sql('SELECT * FROM {user} WHERE firstname = :firstname AND lastname = :lastname',
    ['firstname' => 'Martin', 'lastname' => 'Dougiamas']);
</syntaxhighlight>
=== Strictness ===
Some methods accept the <tt>$strictness</tt> parameter affecting the method behaviour. Supported modes are specified using the constants:
* <tt>MUST_EXIST</tt> - In this mode, the requested record must exist and must be unique. An exception will be thrown if no record is found or multiple matching records are found.
* <tt>IGNORE_MISSING</tt> - In this mode, a missing record is not an error. False boolean is returned if the requested record is not found. If more records are found, a debugging message is displayed.
* <tt>IGNORE_MULTIPLE</tt> - This is not a recommended mode. The function will silently ignore multiple records found and will return just the first one of them.
== Getting a single record ==
=== get_record ===
Return a single database record as an object where all the given conditions are met.
<syntaxhighlight lang="php">$DB->get_record($table, array $conditions, $fields='*', $strictness=IGNORE_MISSING)</syntaxhighlight>
=== get_record_select ===
Return a single database record as an object where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->get_record_select($table, $select, array $params=null, $fields='*', $strictness=IGNORE_MISSING)</syntaxhighlight>
=== get_record_sql ===
Return a single database record as an object using a custom SELECT query.
<syntaxhighlight lang="php">$DB->get_record_sql($sql, array $params=null, $strictness=IGNORE_MISSING)</syntaxhighlight>
== Getting a hashed array of records ==
Each of the following methods return an array of objects. The array is indexed by the first column of the fields returned by the query. To assure consistency, it is a good practice to ensure that your query include an "id column" as the first field. When designing custom tables, make <tt>id</tt> their first column and primary key.
=== get_records ===
Return a list of records as an array of objects where all the given conditions are met.
<syntaxhighlight lang="php">$DB->get_records($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)</syntaxhighlight>
=== get_records_select ===
Return a list of records as an array of objects where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->get_records_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)</syntaxhighlight>
$fields is a comma separated list of fields to return (optional, by default all fields are returned).
=== get_records_sql ===
Return a list of records as an array of objects using a custom SELECT query.
<syntaxhighlight lang="php">$DB->get_records_sql($sql, array $params=null, $limitfrom=0, $limitnum=0)</syntaxhighlight>
=== get_records_list ===
Return a list of records as an array of objects where the given field matches one of the possible values.
<syntaxhighlight lang="php">$DB->get_records_list($table, $field, array $values, $sort='', $fields='*', $limitfrom='', $limitnum='')</syntaxhighlight>
== Getting data as key/value pairs in an associative array ==
=== get_records_menu ===
Return the first two columns from a list of records as an associative array where all the given conditions are met.
<syntaxhighlight lang="php">$DB->get_records_menu($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)</syntaxhighlight>
=== get_records_select_menu ===
Return the first two columns from a list of records as an associative array where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->get_records_select_menu($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)</syntaxhighlight>
=== get_records_sql_menu ===
Return the first two columns from a number of records as an associative array using a custom SELECT query.
<syntaxhighlight lang="php">$DB->get_records_sql_menu($sql, array $params=null, $limitfrom=0, $limitnum=0)</syntaxhighlight>
== Counting records that match the given criteria ==
=== count_records ===
Count the records in a table where all the given conditions are met.
<syntaxhighlight lang="php">$DB->count_records($table, array $conditions=null) </syntaxhighlight>
=== count_records_select ===
Count the records in a table where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->count_records_select($table, $select, array $params=null, $countitem="COUNT('x')")</syntaxhighlight>
=== count_records_sql ===
Counting the records using a custom SELECT COUNT(...) query.
<syntaxhighlight lang="php">$DB->count_records_sql($sql, array $params=null)</syntaxhighlight>
== Checking if a given record exists ==
=== record_exists ===
Test whether a record exists in a table where all the given conditions are met.
<syntaxhighlight lang="php">$DB->record_exists($table, array $conditions=null)</syntaxhighlight>
=== record_exists_select ===
Test whether any records exists in a table where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->record_exists_select($table, $select, array $params=null)</syntaxhighlight>
=== record_exists_sql ===
Test whether the given SELECT query would return any record.
<syntaxhighlight lang="php">$DB->record_exists_sql($sql, array $params=null)</syntaxhighlight>
== Getting a particular field value from one record ==
=== get_field ===
Get a single field value from a table record where all the given conditions are met.
<syntaxhighlight lang="php">$DB->get_field($table, $return, array $conditions, $strictness=IGNORE_MISSING)</syntaxhighlight>
=== get_field_select ===
Get a single field value from a table record where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->get_field_select($table, $return, $select, array $params=null, $strictness=IGNORE_MISSING)</syntaxhighlight>
=== get_field_sql ===
Get a single field value (first field) using a custom SELECT query.
<syntaxhighlight lang="php">$DB->get_field_sql($sql, array $params=null, $strictness=IGNORE_MISSING)</syntaxhighlight>
== Getting field values from multiple records ==
=== get_fieldset_select ===
Return values of the given field as an array where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->get_fieldset_select($table, $return, $select, array $params=null)</syntaxhighlight>
=== get_fieldset_sql ===
Return values of the first column as an array using a custom SELECT field FROM ... query.
<syntaxhighlight lang="php">$DB->get_fieldset_sql($sql, array $params=null)</syntaxhighlight>
== Setting a field value ==
=== set_field ===
Set a single field in every record where all the given conditions are met.
<syntaxhighlight lang="php">$DB->set_field($table, $newfield, $newvalue, array $conditions=null)</syntaxhighlight>
=== set_field_select ===
Set a single field in every table record where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->set_field_select($table, $newfield, $newvalue, $select, array $params=null)</syntaxhighlight>
== Deleting records ==
=== delete_records ===
Delete records from the table where all the given conditions are met.
<syntaxhighlight lang="php">$DB->delete_records($table, array $conditions=null)</syntaxhighlight>
=== delete_records_select ===
Delete records from the table where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->delete_records_select($table, $select, array $params=null)</syntaxhighlight>
== Inserting records ==
=== insert_record ===
Insert the given data object into the table and return the "id" of the newly created record.
<syntaxhighlight lang="php">$DB->insert_record($table, $dataobject, $returnid=true, $bulk=false)</syntaxhighlight>
=== insert_records ===
{{Moodle_2.7}}Insert multiple records into the table as fast as possible. Records are inserted in the given order, but the operation is not atomic. Use transactions if necessary.
<syntaxhighlight lang="php">$DB->insert_records($table, $dataobjects)</syntaxhighlight>
=== insert_record_raw ===
For rare cases when you also need to specify the ID of the record to be inserted.
== Updating records ==
=== update_record ===
Update a record in the table. The data object must have the property "id" set.
<syntaxhighlight lang="php">$DB->update_record($table, $dataobject, $bulk=false)</syntaxhighlight>
== Executing a custom query ==
=== execute ===
* If you need to perform a complex update using arbitrary SQL, you can use the low level "execute" method. Only use this when no specialised method exists.
* Do NOT use this to make changes in database structure, use database_manager methods instead!
<syntaxhighlight lang="php">$DB->execute($sql, array $params=null)</syntaxhighlight>
== Using recordsets ==
If the number of records to be retrieved from DB is high, the 'get_records_xxx() functions above are far from optimal, because they load all the records into the memory via the returned array. Under those circumstances, it is highly recommended to use these get_recordset_xxx() functions instead. They return an iterator to iterate over all the found records and save a lot of memory.

It is '''absolutely important''' to not forget to close the returned recordset iterator after using it. This is to free up a lot of resources in the RDBMS.

A general way to iterate over records using the get_recordset_xxx() functions:
<syntaxhighlight lang="php">
$rs = $DB->get_recordset(....);
foreach ($rs as $record) {
    // Do whatever you want with this record
}
$rs->close();
</syntaxhighlight>
Unlike get_record functions, you cannot check if <tt>$rs == true</tt> or <tt>!empty($rs)</tt> to determine if any records were found. Instead, if you need to, you can use:
<syntaxhighlight lang="php">
if ($rs->valid()) {
    // The recordset contains some records.
}
</syntaxhighlight>
=== get_recordset ===
Return a list of records as a moodle_recordset where all the given conditions are met.
<syntaxhighlight lang="php">$DB->get_recordset($table, array $conditions=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)</syntaxhighlight>
=== get_recordset_select ===
Return a list of records as a moodle_recordset where the given conditions are used in the WHERE clause.
<syntaxhighlight lang="php">$DB->get_recordset_select($table, $select, array $params=null, $sort='', $fields='*', $limitfrom=0, $limitnum=0)</syntaxhighlight>
=== get_recordset_sql ===
Return a list of records as a moodle_recordset using a custom SELECT query.
<syntaxhighlight lang="php">$DB->get_recordset_sql($sql, array $params=null, $limitfrom=0, $limitnum=0)</syntaxhighlight>
=== get_recordset_list ===
Return a list of records as a moodle_recordset where the given field matches one of the possible values.
<syntaxhighlight lang="php">$DB->get_recordset_list($table, $field, array $values, $sort='', $fields='*', $limitfrom='', $limitnum='')</syntaxhighlight>
== Delegated transactions ==
* Please note some databases do not support transactions (such as the MyISAM MySQL database engine), however all server administrators are strongly encouraged to migrate to databases that support transactions (such as the InnoDB MySQL database engine).
* Previous versions supported only one level of transaction. Since Moodle 2.0, the DML layer emulates delegated transactions that allow nesting of transactions.
* Some subsystems (such as messaging) do not support transactions because it is not possible to rollback in external systems.
A transaction is started by:
<syntaxhighlight lang="php">
$transaction = $DB->start_delegated_transaction();
</syntaxhighlight>
and finished by:
<syntaxhighlight lang="php">
$transaction->allow_commit();
</syntaxhighlight>
Usually a transaction is rolled back when an exception is thrown:
<syntaxhighlight lang="php">$transaction->rollback($ex);</syntaxhighlight>
which must be used very carefully because it might break compatibility with databases that do not support transactions. Transactions cannot be used as part of expected code flow; they can be used only as an emergency protection of data consistency.

See more details in [[DB layer 2.0 delegated transactions]] or MDL-20625.
=== Example ===
<syntaxhighlight lang="php">
global $DB;
try {
     $transaction = $DB->start_delegated_transaction();
     $DB->insert_record('foo', $object);
     $DB->insert_record('bar', $otherobject);

     // Assuming the both inserts work, we get to the following line.
     $transaction->allow_commit();

} catch(Exception $e) {
     $transaction->rollback($e);
}
</syntaxhighlight>
== Cross-DB compatibility ==
Moodle supports several SQL servers (MySQL, PostgreSQL, MS-SQL and Oracle). Each of them have some specific syntax in certain cases. In order to achieve cross-db compatibility of the code, following functions must be used to generate the fragments of the query valid for the actual SQL server.
=== sql_bitand ===
Return the SQL text to be used in order to perform a bitwise AND operation between 2 integers.
<syntaxhighlight lang="php">$DB->sql_bitand($int1, $int2)</syntaxhighlight>
=== sql_bitnot ===
Return the SQL text to be used in order to perform a bitwise NOT operation on the given integer.
<syntaxhighlight lang="php">$DB->sql_bitnot($int1)</syntaxhighlight>
=== sql_bitor ===
Return the SQL text to be used in order to perform a bitwise OR operation between 2 integers.
<syntaxhighlight lang="php">$DB->sql_bitor($int1, $int2)</syntaxhighlight>
=== sql_bitxor ===
Return the SQL text to be used in order to perform a bitwise XOR operation between 2 integers.
<syntaxhighlight lang="php">$DB->sql_bitxor($int1, $int2)</syntaxhighlight>
=== sql_null_from_clause ===
Return an empty FROM clause required by some DBs in all SELECT statements.
<syntaxhighlight lang="php">$DB->sql_null_from_clause()</syntaxhighlight>
=== sql_ceil ===
Return the correct CEIL expression applied to the given fieldname.
<syntaxhighlight lang="php">$DB->sql_ceil($fieldname)</syntaxhighlight>
=== sql_equal ===
{{Moodle 3.2}}Return the query fragment to perform cross-db varchar comparisons when case-sensitiveness is important.
<syntaxhighlight lang="php">$DB->sql_equal($fieldname, $param, $casesensitive = true, $accentsensitive = true, $notequal = false)</syntaxhighlight>
=== sql_like ===
Return the query fragment to perform the LIKE comparison.
<syntaxhighlight lang="php">$DB->sql_like($fieldname, $param, $casesensitive = true, $accentsensitive = true, $notlike = false, $escapechar = ' \\ ')</syntaxhighlight>
Example: Searching for records partially matching the given hard-coded literal.
<syntaxhighlight lang="php">$DB->get_records_sql('SELECT id,fullname FROM {course} WHERE '.$DB->sql_like('idnumber', ':idnum'), ['idnum' => 'DEMO-%']);</syntaxhighlight>
See below if you need to compare with a value submitted by the user.
=== sql_like_escape ===
Escape the value submitted by the user so that it can be used for partial comparison and the special characters like '_' or '%' behave as literal characters, not wildcards.
<syntaxhighlight lang="php">$DB->sql_like_escape($text, $escapechar = '\\')</syntaxhighlight>
Example: If you need to perform a partial comparison with a value that has been submitted by the user.
<syntaxhighlight lang="php">
$search = required_param('search', PARAM_RAW);
$DB->get_records_sql('SELECT id,fullname FROM {course} WHERE '.$DB->sql_like('fullname', ':fullname'), ['fullname' => '%'.$DB->sql_like_escape($search).'%']);
</syntaxhighlight>
=== sql_length ===
Return the query fragment to be used to calculate the length of the expression in characters.
<syntaxhighlight lang="php">$DB->sql_length($fieldname)</syntaxhighlight>
=== sql_modulo ===
Return the query fragment to be used to calculate the remainder after division.
<syntaxhighlight lang="php">$DB->sql_modulo($int1, $int2)</syntaxhighlight>
=== sql_position ===
Return the query fragment for searching a string for the location of a substring. If both needle and haystack use placeholders, you must use named placeholders.
<syntaxhighlight lang="php">$DB->sql_position($needle, $haystack)</syntaxhighlight>
=== sql_substr ===
Return the query fragment for extracting a substring from the given expression.
<syntaxhighlight lang="php">$DB->sql_substr($expr, $start, $length=false)</syntaxhighlight>
=== sql_cast_char2int ===
Return the query fragment to cast a CHAR column to INTEGER
<syntaxhighlight lang="php">$DB->sql_cast_char2int($fieldname, $text=false)</syntaxhighlight>
=== sql_cast_char2real ===
Return the query fragment to cast a CHAR column to REAL (float) number
<syntaxhighlight lang="php">$DB->sql_cast_char2real($fieldname, $text=false)</syntaxhighlight>
=== sql_compare_text ===
Return the query fragment to be used when comparing a TEXT (clob) column with a given string or a VARCHAR field (some RDBMs do not allow for direct comparison).
<syntaxhighlight lang="php">$DB->sql_compare_text($fieldname, $numchars=32)</syntaxhighlight>
Example:
<syntaxhighlight lang="php">
$todogroups = $DB->get_records_sql('SELECT id FROM {group} WHERE ' . $DB->sql_compare_text('description') . ' = ' . $DB->sql_compare_text(':description'), ['description' => 'TODO']);
</syntaxhighlight>
=== sql_order_by_text ===
Return the query fragment to be used to get records ordered by a TEXT (clob) column. Note this affects the performance badly and should be avoided if possible.
<syntaxhighlight lang="php">$DB->sql_order_by_text($fieldname, $numchars=32)</syntaxhighlight>
=== sql_concat ===
Return the query fragment to concatenate all given paremeters into one string.
<syntaxhighlight lang="php">$DB->sql_concat(...)</syntaxhighlight>
There is a gotcha if you are trying to concat fields which may be null which result in the entire result being null:
<syntaxhighlight lang="php">$DB->sql_concat('requiredfield', 'optionalfield'); // BAD!</syntaxhighlight>
You must cast or coalesce every nullable argument eg:
<syntaxhighlight lang="php">$DB->sql_concat('requiredfield', "COALESCE(optionalfield, '')"); // Good.</syntaxhighlight>
=== sql_group_concat ===
{{Moodle_3.11}}
Return SQL for performing group concatenation on given field/expression.
<syntaxhighlight lang="php">$DB->sql_group_concat(string $field, string $separator = ', ', string $sort = '')</syntaxhighlight>
=== sql_concat_join ===
Return the query fragment to concatenate all given elements into one string using the given separator.
<syntaxhighlight lang="php">$DB->sql_concat_join($separator="' '", $elements=array())</syntaxhighlight>
=== sql_fullname ===
Return the query fragment to concatenate the given $firstname and $lastname
<syntaxhighlight lang="php">$DB->sql_fullname($first='firstname', $last='lastname')</syntaxhighlight>
===  sql_isempty ===
Return the query fragment to check if the field is empty
<syntaxhighlight lang="php">$DB->sql_isempty($tablename, $fieldname, $nullablefield, $textfield)</syntaxhighlight>
=== sql_isnotempty ===
Return the query fragment to check if the field is not empty
<syntaxhighlight lang="php">$DB->sql_isnotempty($tablename, $fieldname, $nullablefield, $textfield)</syntaxhighlight>
=== get_in_or_equal ===
Return the query fragment to check if a value is IN the given list of items (with a fallback to plain equal comparison if there is just one item)
<syntaxhighlight lang="php">$DB->get_in_or_equal($items, $type=SQL_PARAMS_QM, $prefix='param', $equal=true, $onemptyitems=false)</syntaxhighlight>
Example:
<syntaxhighlight lang="php">
$statuses = ['todo', 'open', 'inprogress', 'intesting'];
list($insql, $inparams) = $DB->get_in_or_equal($statuses);
$sql = "SELECT * FROM {bugtracker_issues} WHERE status $insql";
$bugs = $DB->get_records_sql($sql, $inparams);
</syntaxhighlight>
An example using named params:
<syntaxhighlight lang="php">
...
list($insql, $params) = $DB->get_in_or_equal($contexts, SQL_PARAMS_NAMED, 'ctx');
$contextsql = "AND rc.contextid $insql";
...
</syntaxhighlight>
=== sql_regex_supported ===
Does the current database driver support regex syntax when searching?
<syntaxhighlight lang="php">$DB->sql_regex_supported()</syntaxhighlight>
=== sql_regex ===
Return the query fragment to perform a regex search.
<syntaxhighlight lang="php">$DB->sql_regex($positivematch = true, $casesensitive = false)</syntaxhighlight>
Example: Searching for Page module instances containing links.
<syntaxhighlight lang="php">
if ($DB->sql_regex_supported()) {
    $select = 'content ' . $DB->sql_regex() . ' :pattern';
    $params = ['pattern' => "(src|data)\ *=\ *[\\\"\']https?://"]
} else {
    $select = $DB->sql_like('content', ':pattern', false);
    $params = ['pattern' => '%=%http%://%'];
}

$pages = $DB->get_records_select('page', $select, $params, 'course', 'id, course, name');
</syntaxhighlight>
=== sql_intersect ===
{{Moodle 2.8}}Return the query fragment that allows to find intersection of two or more queries
<syntaxhighlight lang="php">$DB->sql_intersect($selects, $fields)</syntaxhighlight>
== Debugging ==
=== set_debug ===
You can enable a debugging mode to make $DB output the SQL of every executed query, along with some timing information. This can be useful when debugging your code. Obviously, all such calls should be removed before code is submitted for integration.
<syntaxhighlight lang="php">$DB->set_debug(true)</syntaxhighlight>
== Special cases ==
=== get_course ===
From Moodle 2.5.1 onwards, you should use the get_course function instead of using get_record('course', ...) if you want to get a course record based on its ID, especially if there is a significant possibility that the course being retrieved is either the current course for the page, or the site course. Those two course records have probably already been loaded, and using this function will save a database query. 

Additionally, the code is shorter and easier to read.
=== get_courses ===
If you want to get all the current courses in your Moodle, use get_courses() without parameter:
    $courses = get_courses();
== See also ==
* [[SQL coding style]]
* [[Core APIs]]
* [[DML exceptions|DML exceptions]]: New DML code is throwing exceptions instead of returning false if anything goes wrong
* [[DML drivers|DML drivers]]: Database drivers for new DML layer
* [[DML functions - pre 2.0|DML functions - pre 2.0]]: '''(deprecated!)''' For information valid before Moodle 2.0.
* [[DDL functions|DDL functions]]: Where all the functions used to handle DB objects ([[wikipedia:Data_Definition_Language|DDL]]) are defined.
* [[DB layer 2.0 examples|DB layer 2.0 examples]]: To see some code examples using various DML functions.
* [[DB layer 2.0 migration docs|DB layer 2.0 migration docs]]: Information about how to modify your code to work with the new Moodle 2.0 DB layer.
* [[DTL functions|DTL functions]]: Exporting, importing and moving of data stored in SQL databases
[[Category:DB]]
[[Category:XMLDB]]
[[Category:API]]