class MergeQuery

General class for an abstracted MERGE query operation.

An ANSI SQL:2003 compatible database would run the following query:

MERGE INTO table_name_1 USING table_name_2 ON (condition)
  WHEN MATCHED THEN
  UPDATE SET column1 = value1 [, column2 = value2 ...]
  WHEN NOT MATCHED THEN
  INSERT (column1 [, column2 ...]) VALUES (value1 [, value2 ...

Other databases (most notably MySQL, PostgreSQL and SQLite) will emulate this statement by running a SELECT and then INSERT or UPDATE.

By default, the two table names are identical and they are passed into the the constructor. table_name_2 can be specified by the MergeQuery::conditionTable() method. It can be either a string or a subquery.

The condition is built exactly like SelectQuery or UpdateQuery conditions, the UPDATE query part is built similarly like an UpdateQuery and finally the INSERT query part is built similarly like an InsertQuery. However, both UpdateQuery and InsertQuery has a fields method so MergeQuery::updateFields() and MergeQuery::insertFields() needs to be called instead. MergeQuery::fields() can also be called which calls both of these methods as the common case is to use the same column-value pairs for both INSERT and UPDATE. However, this is not mandatory. Another convinient wrapper is MergeQuery::key() which adds the same column-value pairs to the condition and the INSERT query part.

Several methods (key(), fields(), insertFields()) can be called to set a key-value pair for the INSERT query part. Subsequent calls for the same fields override the earlier ones. The same is true for UPDATE and key(), fields() and updateFields().

Hierarchy

Expanded class hierarchy of MergeQuery

Related topics

Database abstraction layer
Allow the use of different database servers using the same code base.

File

includes/database/query.inc, line 1254
Non-specific Database query code. Used by all engines.

Members

Name Modifiers Type Description
MergeQuery::$conditionTable protected property The table or subquery to be used for the condition.
MergeQuery::$defaultFields protected property An array of fields which should be set to their database-defined defaults.
MergeQuery::$expressionFields protected property Array of fields to update to an expression in case of a duplicate record.
MergeQuery::$insertFields protected property An array of fields on which to insert.
MergeQuery::$insertValues protected property An array of values to be inserted.
MergeQuery::$needsUpdate protected property Flag indicating whether an UPDATE is necessary.
MergeQuery::$table protected property The table to be used for INSERT and UPDATE.
MergeQuery::$updateFields protected property An array of fields that will be updated.
MergeQuery::arguments public function Implements QueryConditionInterface::arguments(). Overrides QueryConditionInterface::arguments
MergeQuery::compile public function Implements QueryConditionInterface::compile(). Overrides QueryConditionInterface::compile
MergeQuery::compiled public function Implements QueryConditionInterface::compiled(). Overrides QueryConditionInterface::compiled
MergeQuery::condition public function Implements QueryConditionInterface::condition(). Overrides QueryConditionInterface::condition
MergeQuery::conditions public function Implements QueryConditionInterface::conditions(). Overrides QueryConditionInterface::conditions
MergeQuery::conditionTable protected function Sets the table or subquery to be used for the condition.
MergeQuery::execute public function Runs the query against the database. Overrides Query::execute
MergeQuery::exists public function Implements QueryConditionInterface::exists(). Overrides QueryConditionInterface::exists
MergeQuery::expression public function Specifies fields to be updated as an expression.
MergeQuery::fields public function Sets common field-value pairs in the INSERT and UPDATE query parts.
MergeQuery::insertFields public function Adds a set of field->value pairs to be inserted.
MergeQuery::isNotNull public function Implements QueryConditionInterface::isNotNull(). Overrides QueryConditionInterface::isNotNull
MergeQuery::isNull public function Implements QueryConditionInterface::isNull(). Overrides QueryConditionInterface::isNull
MergeQuery::key public function Sets the key field(s) to be used as conditions for this query.
MergeQuery::notExists public function Implements QueryConditionInterface::notExists(). Overrides QueryConditionInterface::notExists
MergeQuery::STATUS_INSERT constant Returned by execute() if an INSERT query has been executed.
MergeQuery::STATUS_UPDATE constant Returned by execute() if an UPDATE query has been executed.
MergeQuery::updateFields public function Adds a set of field->value pairs to be updated.
MergeQuery::useDefaults public function Specifies fields for which the database-defaults should be used.
MergeQuery::where public function Implements QueryConditionInterface::where(). Overrides QueryConditionInterface::where
MergeQuery::__construct public function Constructs a MergeQuery object. Overrides Query::__construct
MergeQuery::__toString public function Implements PHP magic __toString method to convert the query to a string. Overrides Query::__toString
Query::$comments protected property An array of comments that can be prepended to a query.
Query::$connection protected property The connection object on which to run this query.
Query::$connectionKey protected property The key of the connection object.
Query::$connectionTarget protected property The target of the connection object.
Query::$nextPlaceholder protected property The placeholder counter.
Query::$queryOptions protected property The query options to pass on to the connection object.
Query::$uniqueIdentifier protected property A unique identifier for this query object.
Query::comment public function Adds a comment to the query.
Query::getComments public function Returns a reference to the comments array for the query.
Query::nextPlaceholder public function Gets the next placeholder value for this query object. Overrides QueryPlaceholderInterface::nextPlaceholder
Query::uniqueIdentifier public function Returns a unique identifier for this object. Overrides QueryPlaceholderInterface::uniqueIdentifier
Query::__clone public function Implements the magic __clone function.
Query::__sleep public function Implements the magic __sleep function to disconnect from the database.
Query::__wakeup public function Implements the magic __wakeup function to reconnect to the database.

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