diff --git a/draft/Doctrine/Query/Parser.php b/draft/Doctrine/Query/Parser.php
index 11e609a58..739ff6cdd 100644
--- a/draft/Doctrine/Query/Parser.php
+++ b/draft/Doctrine/Query/Parser.php
@@ -1,4 +1,37 @@
 <?php
+/*
+ *  $Id$
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the LGPL. For more information, see
+ * <http://www.phpdoctrine.org>.
+ */
+
+/**
+ * An LL(k) parser for the context-free grammar of Doctrine Query Language.
+ * Parses a DQL query, reports any errors in it, and generates the corresponding
+ * SQL.
+ *
+ * @package     Doctrine
+ * @subpackage  Query
+ * @author      Janne Vanhala <jpvanhal@cc.hut.fi>
+ * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
+ * @link        www.phpdoctrine.org
+ * @since       1.0
+ * @version     $Revision$
+ */
 class Doctrine_Query_Parser
 {
     /**
@@ -46,21 +79,41 @@ class Doctrine_Query_Parser
     protected $_errorDistance = self::MIN_ERROR_DISTANCE;
 
     /**
-     * A query printer object used to print a parse tree from the input string.
+     * A query printer object used to print a parse tree from the input string
+     * for debugging purposes.
      *
      * @var Doctrine_Query_Printer
      */
     protected $_printer;
 
+    /**
+     * The connection object used by this query.
+     *
+     * @var Doctrine_Connection
+     */
+    protected $_conn;
+
     /**
      * Creates a new query parser object.
      *
      * @param string $input query string to be parsed
+     * @param Doctrine_Connection The connection object the query will use.
      */
-    public function __construct($input)
+    public function __construct($input, Doctrine_Connection $conn = null)
     {
         $this->_scanner = new Doctrine_Query_Scanner($input);
         $this->_printer = new Doctrine_Query_Printer(true);
+
+        if ($conn === null) {
+            $conn = Doctrine_Manager::getInstance()->getCurrentConnection();
+        }
+
+        $this->_conn = $conn;
+    }
+
+    public function getConnection()
+    {
+        return $this->_conn;
     }
 
     public function getProduction($name)
@@ -90,26 +143,20 @@ class Doctrine_Query_Parser
         }
 
         if ($isMatch) {
-            //$this->_printer->println($this->lookahead['value']);
+            $this->_printer->println($this->lookahead['value']);
             $this->lookahead = $this->_scanner->next();
             $this->_errorDistance++;
         } else {
-            $this->syntaxError();
+            $this->logError();
         }
     }
 
-    public function syntaxError()
+    public function logError($message = '')
     {
-        $this->_error('Unexpected "' . $this->lookahead['value'] . '"');
-    }
+        if ($message === '') {
+            $message = 'Unexpected "' . $this->lookahead['value'] . '"';
+        }
 
-    public function semanticalError($message)
-    {
-        $this->_error($message);
-    }
-
-    protected function _error($message)
-    {
         if ($this->_errorDistance >= self::MIN_ERROR_DISTANCE) {
             $message .= 'at line ' . $this->lookahead['line']
                  . ', column ' . $this->lookahead['column'];
diff --git a/draft/Doctrine/Query/Production.php b/draft/Doctrine/Query/Production.php
index e3083343a..c6382349f 100644
--- a/draft/Doctrine/Query/Production.php
+++ b/draft/Doctrine/Query/Production.php
@@ -1,6 +1,35 @@
 <?php
+/*
+ *  $Id$
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the LGPL. For more information, see
+ * <http://www.phpdoctrine.org>.
+ */
+
 /**
- * An abstract base class that all query parser productions extend.
+ * An abstract base class for the productions of the Doctrine Query Language
+ * context-free grammar.
+ *
+ * @package     Doctrine
+ * @subpackage  Query
+ * @author      Janne Vanhala <jpvanhal@cc.hut.fi>
+ * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
+ * @link        www.phpdoctrine.org
+ * @since       1.0
+ * @version     $Revision$
  */
 abstract class Doctrine_Query_Production
 {
@@ -37,7 +66,6 @@ abstract class Doctrine_Query_Production
      */
     public function __call($method, $args)
     {
-        return $this->_parser->getProduction($method)->execute($args);
         $this->_parser->getPrinter()->startProduction($name);
         $retval = $this->_parser->getProduction($method)->execute($args);
         $this->_parser->getPrinter()->endProduction();
@@ -53,13 +81,4 @@ abstract class Doctrine_Query_Production
      * @return mixed
      */
     abstract public function execute(array $params = array());
-
-    protected function _isSubquery()
-    {
-        $lookahead = $this->_parser->lookahead;
-        $next = $this->_parser->getScanner()->peek();
-
-        return $lookahead['value'] === '(' && $next['type'] === Doctrine_Query_Token::T_SELECT;
-    }
-
 }
diff --git a/draft/Doctrine/Query/Production/AbstractSchemaName.php b/draft/Doctrine/Query/Production/AbstractSchemaName.php
new file mode 100644
index 000000000..0d2ef3eee
--- /dev/null
+++ b/draft/Doctrine/Query/Production/AbstractSchemaName.php
@@ -0,0 +1,70 @@
+<?php
+/*
+ *  $Id$
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the LGPL. For more information, see
+ * <http://www.phpdoctrine.org>.
+ */
+
+/**
+ * This class represents the AbstractSchemaName production in DQL grammar.
+ *
+ * <code>
+ * AbstractSchemaName = identifier
+ * </code>
+ *
+ * @package     Doctrine
+ * @subpackage  Query
+ * @author      Janne Vanhala <jpvanhal@cc.hut.fi>
+ * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
+ * @link        www.phpdoctrine.org
+ * @since       1.0
+ * @version     $Revision$
+ */
+class Doctrine_Query_Production_AbstractSchemaName extends Doctrine_Query_Production
+{
+    /**
+     * Executes the AbstractSchemaName production.
+     *
+     * <code>
+     * AbstractSchemaName = identifier
+     * </code>
+     *
+     * @param array $params This production does not take any parameters.
+     * @return Doctrine_Table|null the table object corresponding the identifier
+     * name
+     */
+    public function execute(array $params = array())
+    {
+        $table = null;
+        $token = $this->_parser->lookahead;
+
+        if ($token['type'] === Doctrine_Query_Token::T_IDENTIFIER) {
+
+            $table = $this->_parser->getConnection()->getTable($token['value']);
+
+            if ($table === null) {
+                $this->_parser->logError('Table named "' . $name . '" does not exist.');
+            }
+
+            $this->_parser->match(Doctrine_Query_Token::T_IDENTIFIER);
+        } else {
+            $this->_parser->logError('Identifier expected');
+        }
+
+        return $table;
+    }
+}
diff --git a/draft/Doctrine/Query/Production/IdentificationVariable.php b/draft/Doctrine/Query/Production/IdentificationVariable.php
new file mode 100644
index 000000000..d19fe3cdf
--- /dev/null
+++ b/draft/Doctrine/Query/Production/IdentificationVariable.php
@@ -0,0 +1,19 @@
+<?php
+/**
+ * IdentificationVariable = identifier
+ */
+class Doctrine_Query_Production_IdentificationVariable extends Doctrine_Query_Production
+{
+    public function execute(array $params = array())
+    {
+        $token = $this->_parser->lookahead;
+
+        $this->_parser->match(Doctrine_Query_Token::T_IDENTIFIER);
+
+        /*
+        if ( ! isValidIdentificationVariable($token['value'])) {
+            $this->error('"' . $name . '" is not a identification variable.');
+        }
+        */
+    }
+}
diff --git a/draft/Doctrine/Query/Production/PathExpressionEndingWithAsterisk.php b/draft/Doctrine/Query/Production/PathExpressionEndingWithAsterisk.php
new file mode 100644
index 000000000..70c4541f4
--- /dev/null
+++ b/draft/Doctrine/Query/Production/PathExpressionEndingWithAsterisk.php
@@ -0,0 +1,16 @@
+<?php
+/**
+ * PathExpressionEndingWithAsterisk = {identifier "."} "*"
+ */
+class Doctrine_Query_Production_PathExpressionEndingWithAsterisk extends Doctrine_Query_Production
+{
+    public function execute(array $params = array())
+    {
+        while ($this->_isNextToken(Doctrine_Query_Token::T_IDENTIFIER)) {
+            $this->_parser->match(Doctrine_Query_Token::T_IDENTIFIER);
+            $this->_parser->match('.');
+        }
+
+        $this->_parser->match('*');
+    }
+}
diff --git a/draft/Doctrine/Query/Production/QueryLanguage.php b/draft/Doctrine/Query/Production/QueryLanguage.php
index 0f44291b4..306b14825 100644
--- a/draft/Doctrine/Query/Production/QueryLanguage.php
+++ b/draft/Doctrine/Query/Production/QueryLanguage.php
@@ -18,7 +18,7 @@ class Doctrine_Query_Production_QueryLanguage extends Doctrine_Query_Production
                 $this->DeleteStatement();
             break;
             default:
-                $this->_parser->syntaxError();
+                $this->_parser->logError();
         }
     }
 }
diff --git a/draft/Doctrine/Query/Production/RangeVariableDeclaration.php b/draft/Doctrine/Query/Production/RangeVariableDeclaration.php
index bdb8f9098..b40c14e5a 100644
--- a/draft/Doctrine/Query/Production/RangeVariableDeclaration.php
+++ b/draft/Doctrine/Query/Production/RangeVariableDeclaration.php
@@ -1,18 +1,17 @@
 <?php
 /**
- * RangeVariableDeclaration = PathExpression [["AS" ] identifier]
+ * RangeVariableDeclaration = AbstractSchemaName ["AS"] IdentificationVariable
  */
 class Doctrine_Query_Production_RangeVariableDeclaration extends Doctrine_Query_Production
 {
     public function execute(array $params = array())
     {
-        $this->PathExpression();
+        $this->AbstractSchemaName();
 
         if ($this->_isNextToken(Doctrine_Query_Token::T_AS)) {
             $this->_parser->match(Doctrine_Query_Token::T_AS);
-            $this->_parser->match(Doctrine_Query_Token::T_IDENTIFIER);
-        } elseif ($this->_isNextToken(Doctrine_Query_Token::T_IDENTIFIER)) {
-            $this->_parser->match(Doctrine_Query_Token::T_IDENTIFIER);
         }
+
+        $this->IdentificationVariable();
     }
 }
diff --git a/draft/Doctrine/Query/Production/SelectExpression.php b/draft/Doctrine/Query/Production/SelectExpression.php
index e505f32f1..a125b40bd 100644
--- a/draft/Doctrine/Query/Production/SelectExpression.php
+++ b/draft/Doctrine/Query/Production/SelectExpression.php
@@ -1,12 +1,35 @@
 <?php
 /**
- * SelectExpression  = (Expression | "(" Subselect ")" ) [["AS"] identifier]
+ * SelectExpression = (PathExpressionEndingWithAsterisk | Expression | "(" Subselect ")")
+ *                    [["AS"] IdentificationVariable]
  */
 class Doctrine_Query_Production_SelectExpression extends Doctrine_Query_Production
 {
+    private function _isPathExpressionEndingWithAsterisk()
+    {
+        $token = $this->_parser->lookahead;
+        $this->_parser->getScanner()->resetPeek();
+
+        while (($token['type'] === Doctrine_Query_Token::T_IDENTIFIER) || ($token['value'] === '.')) {
+            $token = $this->_parser->getScanner()->peek();
+        }
+
+        return $token['value'] === '*';
+    }
+
+    private function _isSubquery()
+    {
+        $lookahead = $this->_parser->lookahead;
+        $next = $this->_parser->getScanner()->peek();
+
+        return $lookahead['value'] === '(' && $next['type'] === Doctrine_Query_Token::T_SELECT;
+    }
+
     public function execute(array $params = array())
     {
-        if ($this->_isSubquery()) {
+        if ($this->_isPathExpressionEndingWithAsterisk()) {
+            $this->PathExpressionEndingWithAsterisk();
+        } elseif ($this->_isSubquery()) {
             $this->_parser->match('(');
             $this->Subselect();
             $this->_parser->match(')');
@@ -18,7 +41,7 @@ class Doctrine_Query_Production_SelectExpression extends Doctrine_Query_Producti
             $this->_parser->match(Doctrine_Query_Token::T_AS);
             $this->_parser->match(Doctrine_Query_Token::T_IDENTIFIER);
         } elseif ($this->_isNextToken(Doctrine_Query_Token::T_IDENTIFIER)) {
-            $this->_parser->match(Doctrine_Query_Token::T_IDENTIFIER);
+            $this->IdentificationVariable();
         }
     }
 }
diff --git a/draft/Doctrine/Query/Scanner.php b/draft/Doctrine/Query/Scanner.php
index 68c3972dc..2937c42bd 100644
--- a/draft/Doctrine/Query/Scanner.php
+++ b/draft/Doctrine/Query/Scanner.php
@@ -1,4 +1,35 @@
 <?php
+/*
+ *  $Id$
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the LGPL. For more information, see
+ * <http://www.phpdoctrine.org>.
+ */
+
+/**
+ * ...
+ *
+ * @package     Doctrine
+ * @subpackage  Query
+ * @author      Janne Vanhala <jpvanhal@cc.hut.fi>
+ * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
+ * @link        www.phpdoctrine.org
+ * @since       1.0
+ * @version     $Revision$
+ */
 class Doctrine_Query_Scanner
 {
     /**
diff --git a/draft/Doctrine/Query/Token.php b/draft/Doctrine/Query/Token.php
index de05bef03..e4f6ccb7f 100644
--- a/draft/Doctrine/Query/Token.php
+++ b/draft/Doctrine/Query/Token.php
@@ -50,14 +50,6 @@ final class Doctrine_Query_Token
     const T_SQRT                = 141;
     const T_MOD                 = 142;
     const T_SIZE                = 143;
-    const T_CURRENT_DATE        = 144;
-    const T_CURRENT_TIMESTAMP   = 145;
-    const T_CURRENT_TIME        = 146;
-    const T_SUBSTRING           = 147;
-    const T_CONCAT              = 148;
-    const T_TRIM                = 149;
-    const T_LOWER               = 150;
-    const T_UPPER               = 151;
 
     private function __construct() {}
 }
diff --git a/draft/query-language.txt b/draft/query-language.txt
index d396a35af..c9244789e 100644
--- a/draft/query-language.txt
+++ b/draft/query-language.txt
@@ -1,3 +1,16 @@
+/* Context-free grammar for Doctrine Query Language
+ *
+ * Document syntax:
+ *  - non-terminals begin with an upper case character
+ *  - terminals begin with a lower case character
+ *  - parentheses (...) are used for grouping
+ *  - square brackets [...] are used for defining an optional part, eg. zero or
+ *    one time time
+ *  - curly brackets {...} are used for repetion, eg. zero or more times
+ *  - double quotation marks "..." define a terminal string
+ *  - a vertical bar represents an alternative
+ */
+
 QueryLanguage   = SelectStatement | UpdateStatement | DeleteStatement
 
 SelectStatement = [SelectClause] FromClause [WhereClause] [GroupByClause] [HavingClause] [OrderByClause] [LimitClause]
@@ -20,11 +33,11 @@ OrderByItem = PathExpression ["ASC" | "DESC"]
 GroupByItem = PathExpression
 UpdateItem = PathExpression "=" (Expression | "NULL")
 
-IdentificationVariableDeclaration =  RangeVariableDeclaration {Join}
-RangeVariableDeclaration = PathExpression [["AS" ] identifier<identification-variable>]
+IdentificationVariableDeclaration = RangeVariableDeclaration {Join}
+RangeVariableDeclaration = AbstractSchemaName ["AS"] IdentificationVariable
 
-Join = ["LEFT" | "INNER"] "JOIN" PathExpression "AS" identifier [["ON" | "WITH"] ConditionalExpression] IndexBy
-IndexBy = "INDEXBY" identifier
+Join = ["LEFT" | "INNER"] "JOIN" PathExpression ["AS"] IdentificationVariable [("ON" | "WITH") ConditionalExpression] [IndexBy]
+IndexBy = "INDEXBY" PathExpression
 
 ConditionalExpression = ConditionalTerm {"OR" ConditionalTerm}
 ConditionalTerm       = ConditionalFactor {"AND" ConditionalFactor}
@@ -34,15 +47,16 @@ SimpleConditionalExpression
                       = Expression (ComparisonExpression | BetweenExpression | LikeExpression
                       | InExpression | NullComparisonExpression) | ExistsExpression
 
-Atom = string-literal | numeric-constant | input-parameter
+Atom = string_literal | numeric_constant | input_parameter
 
-Expression  = Expression {("+" | "-" | "*" | "/") Expression}
-Expression  = ("+" | "-") Expression
-Expression  = "(" Expression ")"
-Expression  = PathExpression | Atom | | Function | AggregateExpression
+Expression = Term {("+" | "-") Term}
+Term       = Factor {("*" | "/") Factor}
+Factor     = [("+" | "-")] Primary
+Primary    = PathExpression | Atom | "(" Expression ")" | Function | AggregateExpression
 
-SelectExpression  = (Expression | "(" Subselect ")" ) [["AS"] identifier]
+SelectExpression  = (PathExpressionEndingWithAsterisk | Expression | "(" Subselect ")" ) [["AS"] IdentificationVariable]
 PathExpression = identifier {"." identifier}
+PathExpressionEndingWithAsterisk = {identifier "."} "*"
 
 AggregateExpression = ("AVG" | "MAX" | "MIN" | "SUM") "(" ["DISTINCT"] Expression ")"
                     | "COUNT" "(" ["DISTINCT"] (Expression | "*") ")"
@@ -51,26 +65,8 @@ QuantifiedExpression     = ("ALL" | "ANY" | "SOME") "(" Subselect ")"
 BetweenExpression        = ["NOT"] "BETWEEN" Expression "AND" Expression
 ComparisonExpression     = ComparisonOperator ( QuantifiedExpression | Expression | "(" Subselect ")" )
 InExpression             = ["NOT"] "IN" "(" (Atom {"," Atom} | Subselect) ")"
-LikeExpression           = ["NOT"] "LIKE" Expression ["ESCAPE" escape_character]
+LikeExpression           = ["NOT"] "LIKE" Expression ["ESCAPE" string_literal]
 NullComparisonExpression = "IS" ["NOT"] "NULL"
 ExistsExpression         = ["NOT"] "EXISTS" "(" Subselect ")"
 
-
-Function =
-    "CURRENT_DATE" |
-    "CURRENT_TIME" |
-    "CURRENT_TIMESTAMP" |
-    "LENGTH" "(" Expression ")" |
-    "LOCATE" "(" Expression "," Expression ["," Expression] ")" |
-    "ABS" "(" Expression ")" |
-    "SQRT" "(" Expression ")" |
-    "MOD" "(" Expression "," Expression ")" |
-    "SIZE" "(" Expression ")" |
-    "CONCAT" "(" Expression "," Expression ")" |
-    "SUBSTRING" "(" Expression "," Expression "," "Expression" ")" |
-    "TRIM" "(" [[TrimSpecification] [trim_character] "FROM"] string_primary ")" |
-    "LOWER" "(" string_primary ")" |
-    "UPPER" "(" string_primary ")" |
-    identifier "(" [Expression {"," Expression}]")" // Custom function
-
-TrimSpecification = "LEADING" | "TRAILING" | "BOTH"
+Function = identifier "(" [Expression {"," Expression}] ")"