new functions

Author: djpmsft

articles/data-factory/data-flow-expression-functions.md

@@ -59,6 +59,14 @@ Logical AND operator. Same as &&
 * ``and(true, false) -> false``  
 * ``true && false -> false``  
 ___
+### <code>array</code>
+<code><b>array([<i>&lt;value1&gt;</i> : any], ...) => array</b></code><br/><br/>
+Creates an array of items. All items should be of the same type. If no items are specified, an empty string array is the default. Same as a [] creation operator  
+* ``array('Seattle', 'Washington')``
+* ``['Seattle', 'Washington']``
+* ``['Seattle', 'Washington'][1]``
+* ``'Washington'``
+___
 ### <code>asin</code>
 <code><b>asin(<i>&lt;value1&gt;</i> : number) => double</b></code><br/><br/>
 Calculates an inverse sine value  
@@ -84,6 +92,27 @@ Selects a column value by name in the stream. You can pass a optional stream nam
 * ``toString(byName('Bogus Column'))``  
 * ``toString(byName('Bogus Column', 'DeriveStream'))``  
 ___
+### <code>byNames</code>
+<code><b>byNames(<i>&lt;column names&gt;</i> : array, [<i>&lt;stream name&gt;</i> : string]) => any</b></code><br/><br/>
+Select an array of columns by name in the stream. You can pass a optional stream name as the second argument. If there are multiple matches, the first match is returned. If there are no matches for a column, the entire output is a NULL value. The returned value requires a type conversion functions (toDate, toString, ...).  Column names known at design time should be addressed just by their name. Computed inputs are not supported but you can use parameter substitutions.
+* ``toString(byNames(['parent', 'child']))``
+* ````
+* ``byNames(['parent']) ? string``
+* ````
+* ``toLong(byNames(['income']))``
+* ````
+* ``byNames(['income']) ? long``
+* ````
+* ``toBoolean(byNames(['foster']))``
+* ````
+* ``toLong(byNames($debtCols))``
+* ````
+* ``toString(byNames(['a Column']))``
+* ````
+* ``toString(byNames(['a Column'], 'DeriveStream'))``
+* ````
+* ``byNames(['orderItem']) ? (itemName as string, itemQty as integer)``
+___
 ### <code>byPosition</code>
 <code><b>byPosition(<i>&lt;position&gt;</i> : integer) => any</b></code><br/><br/>
 Selects a column value by its relative position(1 based) in the stream. If the position is out of bounds it returns a NULL value. The returned value has to be type converted by one of the type conversion functions(TO_DATE, TO_STRING ...)Computed inputs are not supported but you can use parameter substitutions  
@@ -129,6 +158,15 @@ ___
 Gets all output columns for a stream. You can pass a optional stream name as the second argument.  
 * ``columnNames()``
 * ``columnNames('DeriveStream')``
+
+___
+### <code>columns</code>
+<code><b>columns([<i>&lt;stream name&gt;</i> : string]) => any</b></code><br/><br/>
+Gets all output columns for a stream. You can pass an optional stream name as the second argument.   
+* ``columns()``
+* ````
+* ``columns('DeriveStream')``
+* ````
 ___
 ### <code>compare</code>
 <code><b>compare(<i>&lt;value1&gt;</i> : any, <i>&lt;value2&gt;</i> : any) => integer</b></code><br/><br/>