anchor.diff:  
   function_call
       : scalar_function_name '(' expression_list? ')'
  +    // https://msdn.microsoft.com/en-us/library/ms173784.aspx
  +    | BINARY_CHECKSUM '(' '*' ')'
       // https://msdn.microsoft.com/en-us/library/hh231076.aspx
       // https://msdn.microsoft.com/en-us/library/ms187928.aspx
  -    | CAST '(' expression AS data_type ('(' DECIMAL ')')? ')'
  +    | CAST '(' expression AS data_type ')'
       | CONVERT '(' data_type ',' expression (',' style=expression)? ')'
  +    // https://msdn.microsoft.com/en-us/library/ms189788.aspx
  +    | CHECKSUM '(' '*' ')'
       // https://msdn.microsoft.com/en-us/library/ms190349.aspx
  -    | COALESCE '(' expression_list? ')'
  +    | COALESCE '(' expression_list ')'
  +    // https://msdn.microsoft.com/en-us/library/ms188751.aspx
  +    | CURRENT_TIMESTAMP
  +    // https://msdn.microsoft.com/en-us/library/ms176050.aspx
  +    | CURRENT_USER
  +    // https://msdn.microsoft.com/en-us/library/ms186819.aspx
  +    | DATEADD '(' datepart ',' expression ',' expression ')'
  +    // https://msdn.microsoft.com/en-us/library/ms189794.aspx
  +    | DATEDIFF '(' datepart ',' expression ',' expression ')'
  +    // https://msdn.microsoft.com/en-us/library/ms174395.aspx
  +    | DATENAME '(' datepart ',' expression ')'
  +    // https://msdn.microsoft.com/en-us/library/ms174420.aspx
  +    | DATEPART '(' datepart ',' expression ')'
  +    // https://msdn.microsoft.com/en-us/library/ms189838.aspx
  +    | IDENTITY '(' data_type (',' seed=DECIMAL)? (',' increment=DECIMAL)? ')'
  +    // https://msdn.microsoft.com/en-us/library/bb839514.aspx
  +    | MIN_ACTIVE_ROWVERSION
       // https://msdn.microsoft.com/en-us/library/ms177562.aspx
       | NULLIF '(' expression ',' expression ')'
  +    // https://msdn.microsoft.com/en-us/library/ms177587.aspx
  +    | SESSION_USER
  +    // https://msdn.microsoft.com/en-us/library/ms179930.aspx
  +    | SYSTEM_USER
  +    ;
  +
  +datepart
  +    : ID
       ;
   
   as_table_alias
  
positive.code:     | FAST_FORWARD
      | FIRST
      | FOLLOWING
      | FORWARD_ONLY
      | FULLSCAN
      | GLOBAL
  
negative.code:     | SELF
      | SERIALIZABLE
      | SNAPSHOT
      | SPATIAL_WINDOW_MAX_CELLS
      | STATIC
      | STATS_STREAM
      | STDEV
  