Remove support for update with joins.

This feature is inconsistently implemented or not implemented across all
drivers. What is implemented consistently across all drivers is the
ability to do update/delete with subquery conditions. This will be the
recommended/documented way to preform multi table update/delete
operations.

lib/Cake/Database/Dialect/PostgresDialectTrait.php

@@ -80,40 +80,6 @@ protected function _selectQueryTranslator($query) {
 		return $query;
 	}
 
-/**
- * Returns an update query that has been transformed for Postgres.
- *
- * Postgres requires joins to be defined in the FROM list instead of
- * as standard joins. This translator will erase joins and replace them with
- * an expression object in the FROM clause.
- *
- * @param Cake\Database\Query $query
- * @return Cake\Database\Query
- */
-	protected function _updateQueryTranslator($query) {
-		$joins = $query->clause('join');
-		if (empty($joins)) {
-			return $query;
-		}
-		$first = array_shift($joins);
-		$sql = sprintf('%s %s', $first['table'], $first['alias']);
-		if (isset($first['conditions']) && count($first['conditions'])) {
-			$query->where($first['conditions']);
-		}
-		foreach ($joins as $i => $join) {
-			$sql .= sprintf(' %s JOIN %s %s', $join['type'], $join['table'], $join['alias']);
-			if (isset($join['conditions']) && count($join['conditions'])) {
-				$sql .= sprintf(' ON %s', $join['conditions']);
-			} else {
-				$sql .= ' ON 1 = 1';
-			}
-		}
-		$expr = $query->newExpr()->add($sql);
-		$query->join([], [], true);
-		$query->from([$expr]);
-		return $query;
-	}
-
 /**
  * Returns a function that will be used as a callback for a results decorator.
  * this function is responsible for deleting the artificial column in results

lib/Cake/Database/Query.php

@@ -289,7 +289,7 @@ protected function _traverseDelete(callable $visitor) {
  * @return void
  */
 	protected function _traverseUpdate(callable $visitor) {
-		$parts = ['update', 'join', 'set', 'from', 'where'];
+		$parts = ['update', 'set', 'where'];
 		foreach ($parts as $name) {
 			call_user_func($visitor, $this->_parts[$name], $name);
 		}

lib/Cake/Test/TestCase/Database/Driver/PostgresTest.php

@@ -136,28 +136,4 @@ public function testConnectionConfigCustom() {
 		$driver->connect();
 	}
 
-	public function testUpdateWithJoin() {
-		$driver = $this->getMock('Cake\Database\driver\Postgres', ['_connect', 'connection']);
-		$connection = new Connection(Configure::read('Datasource.test'));
-		$connection->driver($driver);
-
-		$query = new Query($connection);
-
-		$query->update('articles')
-			->set('title', 'New title')
-			->join([
-				'table' => 'authors',
-				'alias' => 'a',
-				'conditions' => 'author_id = a.id'
-			])
-			->join('comments')
-			->where(['articles.id' => 1]);
-		$result = $query->sql(true);
-
-		$this->assertContains('UPDATE articles SET title = :', $result);
-		$this->assertContains('FROM authors a INNER JOIN comments  ON 1 = 1', $result);
-		$this->assertContains('WHERE (articles.id = :', $result);
-		$this->assertContains('AND author_id = a.id)', $result);
-	}
-
 }

lib/Cake/Test/TestCase/Database/QueryTest.php

@@ -1635,35 +1635,6 @@ public function testUpdateWithExpression() {
 		$this->assertCount(1, $result);
 	}
 
-/**
- * Test updates with joins.
- *
- * @return void
- */
-	public function testUpdateWithJoins() {
-		$config = Configure::read('Datasource.test');
-		$this->skipIf(strpos($config['datasource'], 'Sqlite') !== false, 'Sqlite update with join does not work.');
-
-		$query = new Query($this->connection);
-
-		$query->update('articles')
-			->set('title', 'New title')
-			->join([
-				'table' => 'authors',
-				'alias' => 'a',
-				'conditions' => 'author_id = a.id'
-			])
-			->where(['articles.id' => 1]);
-		$result = $query->sql(false);
-
-		$this->assertContains('UPDATE articles INNER JOIN authors a ON author_id = a.id', $result);
-		$this->assertContains('SET title = :', $result);
-		$this->assertContains('WHERE articles.id = :', $result);
-
-		$result = $query->execute();
-		$this->assertCount(1, $result);
-	}
-
 /**
  * You cannot call values() before insert() it causes all sorts of pain.
  *