Documentation & API reference
schema.inc
Same filename in this branch
File
drupal/includes/database/schema.incView source
<?php
/**
* @file
* Generic Database schema code.
*/
require_once dirname(__FILE__) . '/query.inc';
/**
* @defgroup schemaapi Schema API
* @{
* API to handle database schemas.
*
* A Drupal schema definition is an array structure representing one or
* more tables and their related keys and indexes. A schema is defined by
* hook_schema(), which usually lives in a modulename.install file.
*
* By implementing hook_schema() and specifying the tables your module
* declares, you can easily create and drop these tables on all
* supported database engines. You don't have to deal with the
* different SQL dialects for table creation and alteration of the
* supported database engines.
*
* hook_schema() should return an array with a key for each table that
* the module defines.
*
* The following keys are defined:
* - 'description': A string in non-markup plain text describing this table
* and its purpose. References to other tables should be enclosed in
* curly-brackets. For example, the node_revisions table
* description field might contain "Stores per-revision title and
* body data for each {node}."
* - 'fields': An associative array ('fieldname' => specification)
* that describes the table's database columns. The specification
* is also an array. The following specification parameters are defined:
* - 'description': A string in non-markup plain text describing this field
* and its purpose. References to other tables should be enclosed in
* curly-brackets. For example, the node table vid field
* description might contain "Always holds the largest (most
* recent) {node_revision}.vid value for this nid."
* - 'type': The generic datatype: 'char', 'varchar', 'text', 'blob', 'int',
* 'float', 'numeric', or 'serial'. Most types just map to the according
* database engine specific datatypes. Use 'serial' for auto incrementing
* fields. This will expand to 'INT auto_increment' on MySQL.
* - 'mysql_type', 'pgsql_type', 'sqlite_type', etc.: If you need to
* use a record type not included in the officially supported list
* of types above, you can specify a type for each database
* backend. In this case, you can leave out the type parameter,
* but be advised that your schema will fail to load on backends that
* do not have a type specified. A possible solution can be to
* use the "text" type as a fallback.
* - 'serialize': A boolean indicating whether the field will be stored as
* a serialized string.
* - 'size': The data size: 'tiny', 'small', 'medium', 'normal',
* 'big'. This is a hint about the largest value the field will
* store and determines which of the database engine specific
* datatypes will be used (e.g. on MySQL, TINYINT vs. INT vs. BIGINT).
* 'normal', the default, selects the base type (e.g. on MySQL,
* INT, VARCHAR, BLOB, etc.).
* Not all sizes are available for all data types. See
* DatabaseSchema::getFieldTypeMap() for possible combinations.
* - 'not null': If true, no NULL values will be allowed in this
* database column. Defaults to false.
* - 'default': The field's default value. The PHP type of the
* value matters: '', '0', and 0 are all different. If you
* specify '0' as the default value for a type 'int' field it
* will not work because '0' is a string containing the
* character "zero", not an integer.
* - 'length': The maximal length of a type 'char', 'varchar' or 'text'
* field. Ignored for other field types.
* - 'unsigned': A boolean indicating whether a type 'int', 'float'
* and 'numeric' only is signed or unsigned. Defaults to
* FALSE. Ignored for other field types.
* - 'precision', 'scale': For type 'numeric' fields, indicates
* the precision (total number of significant digits) and scale
* (decimal digits right of the decimal point). Both values are
* mandatory. Ignored for other field types.
* - 'binary': A boolean indicating that MySQL should force 'char',
* 'varchar' or 'text' fields to use case-sensitive binary collation.
* This has no effect on other database types for which case sensitivity
* is already the default behavior.
* All parameters apart from 'type' are optional except that type
* 'numeric' columns must specify 'precision' and 'scale', and type
* 'varchar' must specify the 'length' parameter.
* - 'primary key': An array of one or more key column specifiers (see below)
* that form the primary key.
* - 'unique keys': An associative array of unique keys ('keyname' =>
* specification). Each specification is an array of one or more
* key column specifiers (see below) that form a unique key on the table.
* - 'foreign keys': An associative array of relations ('my_relation' =>
* specification). Each specification is an array containing the name of
* the referenced table ('table'), and an array of column mappings
* ('columns'). Column mappings are defined by key pairs ('source_column' =>
* 'referenced_column'). This key is for documentation purposes only; foreign
* keys are not created in the database, nor are they enforced by Drupal.
* - 'indexes': An associative array of indexes ('indexname' =>
* specification). Each specification is an array of one or more
* key column specifiers (see below) that form an index on the
* table.
*
* A key column specifier is either a string naming a column or an
* array of two elements, column name and length, specifying a prefix
* of the named column.
*
* As an example, here is a SUBSET of the schema definition for
* Drupal's 'node' table. It show four fields (nid, vid, type, and
* title), the primary key on field 'nid', a unique key named 'vid' on
* field 'vid', and two indexes, one named 'nid' on field 'nid' and
* one named 'node_title_type' on the field 'title' and the first four
* bytes of the field 'type':
*
* @code
* $schema['node'] = array(
* 'description' => 'The base table for nodes.',
* 'fields' => array(
* 'nid' => array('type' => 'serial', 'unsigned' => TRUE, 'not null' => TRUE),
* 'vid' => array('type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE,'default' => 0),
* 'type' => array('type' => 'varchar','length' => 32,'not null' => TRUE, 'default' => ''),
* 'language' => array('type' => 'varchar','length' => 12,'not null' => TRUE,'default' => ''),
* 'title' => array('type' => 'varchar','length' => 255,'not null' => TRUE, 'default' => ''),
* 'uid' => array('type' => 'int', 'not null' => TRUE, 'default' => 0),
* 'status' => array('type' => 'int', 'not null' => TRUE, 'default' => 1),
* 'created' => array('type' => 'int', 'not null' => TRUE, 'default' => 0),
* 'changed' => array('type' => 'int', 'not null' => TRUE, 'default' => 0),
* 'comment' => array('type' => 'int', 'not null' => TRUE, 'default' => 0),
* 'promote' => array('type' => 'int', 'not null' => TRUE, 'default' => 0),
* 'moderate' => array('type' => 'int', 'not null' => TRUE,'default' => 0),
* 'sticky' => array('type' => 'int', 'not null' => TRUE, 'default' => 0),
* 'tnid' => array('type' => 'int', 'unsigned' => TRUE, 'not null' => TRUE, 'default' => 0),
* 'translate' => array('type' => 'int', 'not null' => TRUE, 'default' => 0),
* ),
* 'indexes' => array(
* 'node_changed' => array('changed'),
* 'node_created' => array('created'),
* 'node_moderate' => array('moderate'),
* 'node_frontpage' => array('promote', 'status', 'sticky', 'created'),
* 'node_status_type' => array('status', 'type', 'nid'),
* 'node_title_type' => array('title', array('type', 4)),
* 'node_type' => array(array('type', 4)),
* 'uid' => array('uid'),
* 'tnid' => array('tnid'),
* 'translate' => array('translate'),
* ),
* 'unique keys' => array(
* 'vid' => array('vid'),
* ),
* // For documentation purposes only; foreign keys are not created in the
* // database.
* 'foreign keys' => array(
* 'node_revision' => array(
* 'table' => 'node_revision',
* 'columns' => array('vid' => 'vid'),
* ),
* 'node_author' => array(
* 'table' => 'users',
* 'columns' => array('uid' => 'uid'),
* ),
* ),
* 'primary key' => array('nid'),
* );
* @endcode
*
* @see drupal_install_schema()
*/
/**
* Base class for database schema definitions.
*/
abstract class DatabaseSchema implements QueryPlaceholderInterface {
protected $connection;
/**
* The placeholder counter.
*/
protected $placeholder = 0;
/**
* Definition of prefixInfo array structure.
*
* Rather than redefining DatabaseSchema::getPrefixInfo() for each driver,
* by defining the defaultSchema variable only MySQL has to re-write the
* method.
*
* @see DatabaseSchema::getPrefixInfo()
*/
protected $defaultSchema = 'public';
/**
* A unique identifier for this query object.
*/
protected $uniqueIdentifier;
public function __construct($connection) {
$this->uniqueIdentifier = uniqid('', TRUE);
$this->connection = $connection;
}
/**
* Implements the magic __clone function.
*/
public function __clone() {
$this->uniqueIdentifier = uniqid('', TRUE);
}
/**
* Implements QueryPlaceHolderInterface::uniqueIdentifier().
*/
public function uniqueIdentifier() {
return $this->uniqueIdentifier;
}
/**
* Implements QueryPlaceHolderInterface::nextPlaceholder().
*/
public function nextPlaceholder() {
return $this->placeholder++;
}
/**
* Get information about the table name and schema from the prefix.
*
* @param
* Name of table to look prefix up for. Defaults to 'default' because thats
* default key for prefix.
* @param $add_prefix
* Boolean that indicates whether the given table name should be prefixed.
*
* @return
* A keyed array with information about the schema, table name and prefix.
*/
protected function getPrefixInfo($table = 'default', $add_prefix = TRUE) {
$info = array(
'schema' => $this->defaultSchema,
'prefix' => $this->connection
->tablePrefix($table),
);
if ($add_prefix) {
$table = $info['prefix'] . $table;
}
// If the prefix contains a period in it, then that means the prefix also
// contains a schema reference in which case we will change the schema key
// to the value before the period in the prefix. Everything after the dot
// will be prefixed onto the front of the table.
if (($pos = strpos($table, '.')) !== FALSE) {
// Grab everything before the period.
$info['schema'] = substr($table, 0, $pos);
// Grab everything after the dot.
$info['table'] = substr($table, ++$pos);
}
else {
$info['table'] = $table;
}
return $info;
}
/**
* Create names for indexes, primary keys and constraints.
*
* This prevents using {} around non-table names like indexes and keys.
*/
function prefixNonTable($table) {
$args = func_get_args();
$info = $this
->getPrefixInfo($table);
$args[0] = $info['table'];
return implode('_', $args);
}
/**
* Build a condition to match a table name against a standard information_schema.
*
* The information_schema is a SQL standard that provides information about the
* database server and the databases, schemas, tables, columns and users within
* it. This makes information_schema a useful tool to use across the drupal
* database drivers and is used by a few different functions. The function below
* describes the conditions to be meet when querying information_schema.tables
* for drupal tables or information associated with drupal tables. Even though
* this is the standard method, not all databases follow standards and so this
* method should be overwritten by a database driver if the database provider
* uses alternate methods. Because information_schema.tables is used in a few
* different functions, a database driver will only need to override this function
* to make all the others work. For example see includes/databases/mysql/schema.inc.
*
* @param $table_name
* The name of the table in question.
* @param $operator
* The operator to apply on the 'table' part of the condition.
* @param $add_prefix
* Boolean to indicate whether the table name needs to be prefixed.
*
* @return QueryConditionInterface
* A DatabaseCondition object.
*/
protected function buildTableNameCondition($table_name, $operator = '=', $add_prefix = TRUE) {
$info = $this->connection
->getConnectionOptions();
// Retrieve the table name and schema
$table_info = $this
->getPrefixInfo($table_name, $add_prefix);
$condition = new DatabaseCondition('AND');
$condition
->condition('table_catalog', $info['database']);
$condition
->condition('table_schema', $table_info['schema']);
$condition
->condition('table_name', $table_info['table'], $operator);
return $condition;
}
/**
* Check if a table exists.
*
* @param $table
* The name of the table in drupal (no prefixing).
*
* @return
* TRUE if the given table exists, otherwise FALSE.
*/
public function tableExists($table) {
$condition = $this
->buildTableNameCondition($table);
$condition
->compile($this->connection, $this);
// Normally, we would heartily discourage the use of string
// concatenation for conditionals like this however, we
// couldn't use db_select() here because it would prefix
// information_schema.tables and the query would fail.
// Don't use {} around information_schema.tables table.
return (bool) $this->connection
->query("SELECT 1 FROM information_schema.tables WHERE " . (string) $condition, $condition
->arguments())
->fetchField();
}
/**
* Find all tables that are like the specified base table name.
*
* @param $table_expression
* An SQL expression, for example "simpletest%" (without the quotes).
* BEWARE: this is not prefixed, the caller should take care of that.
*
* @return
* Array, both the keys and the values are the matching tables.
*/
public function findTables($table_expression) {
$condition = $this
->buildTableNameCondition($table_expression, 'LIKE', FALSE);
$condition
->compile($this->connection, $this);
// Normally, we would heartily discourage the use of string
// concatenation for conditionals like this however, we
// couldn't use db_select() here because it would prefix
// information_schema.tables and the query would fail.
// Don't use {} around information_schema.tables table.
return $this->connection
->query("SELECT table_name FROM information_schema.tables WHERE " . (string) $condition, $condition
->arguments())
->fetchAllKeyed(0, 0);
}
/**
* Check if a column exists in the given table.
*
* @param $table
* The name of the table in drupal (no prefixing).
* @param $name
* The name of the column.
*
* @return
* TRUE if the given column exists, otherwise FALSE.
*/
public function fieldExists($table, $column) {
$condition = $this
->buildTableNameCondition($table);
$condition
->condition('column_name', $column);
$condition
->compile($this->connection, $this);
// Normally, we would heartily discourage the use of string
// concatenation for conditionals like this however, we
// couldn't use db_select() here because it would prefix
// information_schema.tables and the query would fail.
// Don't use {} around information_schema.columns table.
return (bool) $this->connection
->query("SELECT 1 FROM information_schema.columns WHERE " . (string) $condition, $condition
->arguments())
->fetchField();
}
/**
* Returns a mapping of Drupal schema field names to DB-native field types.
*
* Because different field types do not map 1:1 between databases, Drupal has
* its own normalized field type names. This function returns a driver-specific
* mapping table from Drupal names to the native names for each database.
*
* @return array
* An array of Schema API field types to driver-specific field types.
*/
public abstract function getFieldTypeMap();
/**
* Rename a table.
*
* @param $table
* The table to be renamed.
* @param $new_name
* The new name for the table.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table doesn't exist.
* @throws DatabaseSchemaObjectExistsException
* If a table with the specified new name already exists.
*/
public abstract function renameTable($table, $new_name);
/**
* Drop a table.
*
* @param $table
* The table to be dropped.
*
* @return
* TRUE if the table was successfully dropped, FALSE if there was no table
* by that name to begin with.
*/
public abstract function dropTable($table);
/**
* Add a new field to a table.
*
* @param $table
* Name of the table to be altered.
* @param $field
* Name of the field to be added.
* @param $spec
* The field specification array, as taken from a schema definition.
* The specification may also contain the key 'initial', the newly
* created field will be set to the value of the key in all rows.
* This is most useful for creating NOT NULL columns with no default
* value in existing tables.
* @param $keys_new
* (optional) Keys and indexes specification to be created on the
* table along with adding the field. The format is the same as a
* table specification but without the 'fields' element. If you are
* adding a type 'serial' field, you MUST specify at least one key
* or index including it in this array. See db_change_field() for more
* explanation why.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table doesn't exist.
* @throws DatabaseSchemaObjectExistsException
* If the specified table already has a field by that name.
*/
public abstract function addField($table, $field, $spec, $keys_new = array());
/**
* Drop a field.
*
* @param $table
* The table to be altered.
* @param $field
* The field to be dropped.
*
* @return
* TRUE if the field was successfully dropped, FALSE if there was no field
* by that name to begin with.
*/
public abstract function dropField($table, $field);
/**
* Set the default value for a field.
*
* @param $table
* The table to be altered.
* @param $field
* The field to be altered.
* @param $default
* Default value to be set. NULL for 'default NULL'.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table or field doesn't exist.
*/
public abstract function fieldSetDefault($table, $field, $default);
/**
* Set a field to have no default value.
*
* @param $table
* The table to be altered.
* @param $field
* The field to be altered.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table or field doesn't exist.
*/
public abstract function fieldSetNoDefault($table, $field);
/**
* Checks if an index exists in the given table.
*
* @param $table
* The name of the table in drupal (no prefixing).
* @param $name
* The name of the index in drupal (no prefixing).
*
* @return
* TRUE if the given index exists, otherwise FALSE.
*/
public abstract function indexExists($table, $name);
/**
* Add a primary key.
*
* @param $table
* The table to be altered.
* @param $fields
* Fields for the primary key.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table doesn't exist.
* @throws DatabaseSchemaObjectExistsException
* If the specified table already has a primary key.
*/
public abstract function addPrimaryKey($table, $fields);
/**
* Drop the primary key.
*
* @param $table
* The table to be altered.
*
* @return
* TRUE if the primary key was successfully dropped, FALSE if there was no
* primary key on this table to begin with.
*/
public abstract function dropPrimaryKey($table);
/**
* Add a unique key.
*
* @param $table
* The table to be altered.
* @param $name
* The name of the key.
* @param $fields
* An array of field names.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table doesn't exist.
* @throws DatabaseSchemaObjectExistsException
* If the specified table already has a key by that name.
*/
public abstract function addUniqueKey($table, $name, $fields);
/**
* Drop a unique key.
*
* @param $table
* The table to be altered.
* @param $name
* The name of the key.
*
* @return
* TRUE if the key was successfully dropped, FALSE if there was no key by
* that name to begin with.
*/
public abstract function dropUniqueKey($table, $name);
/**
* Add an index.
*
* @param $table
* The table to be altered.
* @param $name
* The name of the index.
* @param $fields
* An array of field names.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table doesn't exist.
* @throws DatabaseSchemaObjectExistsException
* If the specified table already has an index by that name.
*/
public abstract function addIndex($table, $name, $fields);
/**
* Drop an index.
*
* @param $table
* The table to be altered.
* @param $name
* The name of the index.
*
* @return
* TRUE if the index was successfully dropped, FALSE if there was no index
* by that name to begin with.
*/
public abstract function dropIndex($table, $name);
/**
* Change a field definition.
*
* IMPORTANT NOTE: To maintain database portability, you have to explicitly
* recreate all indices and primary keys that are using the changed field.
*
* That means that you have to drop all affected keys and indexes with
* db_drop_{primary_key,unique_key,index}() before calling db_change_field().
* To recreate the keys and indices, pass the key definitions as the
* optional $keys_new argument directly to db_change_field().
*
* For example, suppose you have:
* @code
* $schema['foo'] = array(
* 'fields' => array(
* 'bar' => array('type' => 'int', 'not null' => TRUE)
* ),
* 'primary key' => array('bar')
* );
* @endcode
* and you want to change foo.bar to be type serial, leaving it as the
* primary key. The correct sequence is:
* @code
* db_drop_primary_key('foo');
* db_change_field('foo', 'bar', 'bar',
* array('type' => 'serial', 'not null' => TRUE),
* array('primary key' => array('bar')));
* @endcode
*
* The reasons for this are due to the different database engines:
*
* On PostgreSQL, changing a field definition involves adding a new field
* and dropping an old one which* causes any indices, primary keys and
* sequences (from serial-type fields) that use the changed field to be dropped.
*
* On MySQL, all type 'serial' fields must be part of at least one key
* or index as soon as they are created. You cannot use
* db_add_{primary_key,unique_key,index}() for this purpose because
* the ALTER TABLE command will fail to add the column without a key
* or index specification. The solution is to use the optional
* $keys_new argument to create the key or index at the same time as
* field.
*
* You could use db_add_{primary_key,unique_key,index}() in all cases
* unless you are converting a field to be type serial. You can use
* the $keys_new argument in all cases.
*
* @param $table
* Name of the table.
* @param $field
* Name of the field to change.
* @param $field_new
* New name for the field (set to the same as $field if you don't want to change the name).
* @param $spec
* The field specification for the new field.
* @param $keys_new
* (optional) Keys and indexes specification to be created on the
* table along with changing the field. The format is the same as a
* table specification but without the 'fields' element.
*
* @throws DatabaseSchemaObjectDoesNotExistException
* If the specified table or source field doesn't exist.
* @throws DatabaseSchemaObjectExistsException
* If the specified destination field already exists.
*/
public abstract function changeField($table, $field, $field_new, $spec, $keys_new = array());
/**
* Create a new table from a Drupal table definition.
*
* @param $name
* The name of the table to create.
* @param $table
* A Schema API table definition array.
*
* @throws DatabaseSchemaObjectExistsException
* If the specified table already exists.
*/
public function createTable($name, $table) {
if ($this
->tableExists($name)) {
throw new DatabaseSchemaObjectExistsException(t('Table @name already exists.', array(
'@name' => $name,
)));
}
$statements = $this
->createTableSql($name, $table);
foreach ($statements as $statement) {
$this->connection
->query($statement);
}
}
/**
* Return an array of field names from an array of key/index column specifiers.
*
* This is usually an identity function but if a key/index uses a column prefix
* specification, this function extracts just the name.
*
* @param $fields
* An array of key/index column specifiers.
*
* @return
* An array of field names.
*/
public function fieldNames($fields) {
$return = array();
foreach ($fields as $field) {
if (is_array($field)) {
$return[] = $field[0];
}
else {
$return[] = $field;
}
}
return $return;
}
/**
* Prepare a table or column comment for database query.
*
* @param $comment
* The comment string to prepare.
* @param $length
* Optional upper limit on the returned string length.
*
* @return
* The prepared comment.
*/
public function prepareComment($comment, $length = NULL) {
return $this->connection
->quote($comment);
}
}
/**
* Exception thrown if an object being created already exists.
*
* For example, this exception should be thrown whenever there is an attempt to
* create a new database table, field, or index that already exists in the
* database schema.
*/
class DatabaseSchemaObjectExistsException extends Exception {
}
/**
* Exception thrown if an object being modified doesn't exist yet.
*
* For example, this exception should be thrown whenever there is an attempt to
* modify a database table, field, or index that does not currently exist in
* the database schema.
*/
class DatabaseSchemaObjectDoesNotExistException extends Exception {
}
/**
* @} End of "defgroup schemaapi".
*/Classes
Name |
Description |
|---|---|
| DatabaseSchema | Base class for database schema definitions. |
| DatabaseSchemaObjectDoesNotExistException | Exception thrown if an object being modified doesn't exist yet. |
| DatabaseSchemaObjectExistsException | Exception thrown if an object being created already exists. |