Update datename-transact-sql.md

fbsolo · web-flow · commit 89289b95b585 · 2018-06-01T21:30:56.000-07:00
Text revisions to tighten and optimize the reading flow of the material.

Note: the Return Value block now says

"The return value depends on SET DATEFORMAT if date is a string literal of some formats"

and 'some formats' needs explanation and definition. I looked at earlier versions of this file and they have the same problem. I Googled but I did not find a clear answer. If someone could give me some guidance, I'll revise and send a new PR.

Thank you!
diff --git a/docs/t-sql/functions/datename-transact-sql.md b/docs/t-sql/functions/datename-transact-sql.md
@@ -34,9 +34,9 @@ monikerRange: ">= aps-pdw-2016 || = azuresqldb-current || = azure-sqldw-latest |
 # DATENAME (Transact-SQL)
 [!INCLUDE[tsql-appliesto-ss2008-all-md](../../includes/tsql-appliesto-ss2008-all-md.md)]
 
-Returns a character string that represents the specified *datepart* of the specified *date*
-  
-For an overview of all [!INCLUDE[tsql](../../includes/tsql-md.md)] date and time data types and functions, see [Date and Time Data Types and Functions &#40;Transact-SQL&#41;](../../t-sql/functions/date-and-time-data-types-and-functions-transact-sql.md).
+This function returns a character string representing the specified *datepart* of the specified *date*.
+
+See [Date and Time Data Types and Functions &#40;Transact-SQL&#41;](../../t-sql/functions/date-and-time-data-types-and-functions-transact-sql.md) for an overview of all [!INCLUDE[tsql](../../includes/tsql-md.md)] date and time data types and functions.
   
 ![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md)
   
@@ -48,7 +48,10 @@ DATENAME ( datepart , date )
   
 ## Arguments  
 *datepart*  
-Is the part of the *date* to return. The following table lists all valid *datepart* arguments. User-defined variable equivalents are not valid.
+The specific part of the *date* argument that `DATENAME` will return. This table lists all valid *datepart* arguments.
+
+> [!NOTE]
+> `DATENAME` does not accept user-defined variable equivalents for the *datepart* arguments.
   
 |*datepart*|Abbreviations|  
 |---|---|
@@ -69,8 +72,17 @@ Is the part of the *date* to return. The following table lists all valid *datepa
 |**ISO_WEEK**|**ISOWK, ISOWW**|  
   
 *date*  
-Is an expression that can be resolved to a **time**, **date**, **smalldatetime**, **datetime**, **datetime2**, or **datetimeoffset** value. *date* can be an expression, column expression, user-defined variable, or string literal.  
-To avoid ambiguity, use four-digit years. For information about two-digit years, see [Configure the two digit year cutoff Server Configuration Option](../../database-engine/configure-windows/configure-the-two-digit-year-cutoff-server-configuration-option.md).
+
+An expression that can resolve to one of the following data types: 
+
++ **date**
++ **datetime**
++ **datetimeoffset**
++ **datetime2** 
++ **smalldatetime**
++ **time**
+
+For *date*, `DATENAME` will accept a column expression, expression, string literal, or user-defined variable. Use four-digit years to avoid ambiguity issues. See [Configure the two digit year cutoff Server Configuration Option](../../database-engine/configure-windows/configure-the-two-digit-year-cutoff-server-configuration-option.md) for information about two-digit years.
   
 ## Return Type  
 **nvarchar**
@@ -79,20 +91,20 @@ To avoid ambiguity, use four-digit years. For information about two-digit years,
   
 -   Each *datepart* and its abbreviations return the same value.  
   
-The return value depends on the language environment set by using [SET LANGUAGE](../../t-sql/statements/set-language-transact-sql.md) and by the [Configure the default language Server Configuration Option](../../database-engine/configure-windows/configure-the-default-language-server-configuration-option.md) of the login. The return value is dependant on [SET DATEFORMAT](../../t-sql/statements/set-dateformat-transact-sql.md) if *date* is a string literal of some formats. SET DATEFORMAT does not affect the return value when the date is a column expression of a date or time data type.
+The return value depends on the language environment set by using [SET LANGUAGE](../../t-sql/statements/set-language-transact-sql.md), and by the [Configure the default language Server Configuration Option](../../database-engine/configure-windows/configure-the-default-language-server-configuration-option.md) of the login. The return value depends on [SET DATEFORMAT](../../t-sql/statements/set-dateformat-transact-sql.md) if *date* is a string literal of some formats. SET DATEFORMAT does not change the return value when the date is a column expression of a date or time data type.
   
-When the *date* parameter has a **date** data type argument, the return value depends on the setting specified by using [SET DATEFIRST](../../t-sql/statements/set-datefirst-transact-sql.md).
+When the *date* parameter has a **date** data type argument, the return value depends on the setting specified by [SET DATEFIRST](../../t-sql/statements/set-datefirst-transact-sql.md).
   
 ## TZoffset datepart Argument  
-If *datepart* argument is **TZoffset** (**tz**) and the *date* argument has no time zone offset, 0 is returned.
+If the *datepart* argument is **TZoffset** (**tz**) and the *date* argument has no time zone offset, `DATEADD` returns 0.
   
 ## smalldatetime date Argument  
-When *date* is [smalldatetime](../../t-sql/data-types/smalldatetime-transact-sql.md), seconds are returned as 00.
+When *date* is [smalldatetime](../../t-sql/data-types/smalldatetime-transact-sql.md), `DATENAME` returns seconds as 00.
   
 ## Default Returned for a datepart That Is Not in the date Argument  
-If the data type of the *date* argument does not have the specified *datepart*, the default for that *datepart* will be returned only when a literal is specified for *date*.
+If the data type of the *date* argument does not have the specified *datepart*, `DATENAME` will return the default for that *datepart* only if the *date* argument has a literal .
   
-For example, the default year-month-day for any **date** data type is 1900-01-01. The following statement has date part arguments for *datepart*, a time argument for *date*, and returns `1900, January, 1, 1, Monday`.
+For example, the default year-month-day for any **date** data type is 1900-01-01. This statement has date part arguments for *datepart*, a time argument for *date*, and `DATENAME` returns `1900, January, 1, 1, Monday`.
   
 ```sql
 SELECT DATENAME(year, '12:10:30.123')  
@@ -102,20 +114,27 @@ SELECT DATENAME(year, '12:10:30.123')
     ,DATENAME(weekday, '12:10:30.123');  
 ```  
   
-If *date* is specified as a variable or table column and the data type for that variable or column does not have the specified *datepart*, error 9810 is returned. The following code example fails because the date part year is not a valid for the **time** data type that is declared for the variable *@t*.
+If *date* is specified as a variable or table column, and the data type for that variable or column does not have the specified *datepart*, `DATENAME` will return error 9810. In this example, variable *@t* has a **time** data type. The example fails because the date part year is invalid for the **time** data type:
   
 ```sql
 DECLARE @t time = '12:10:30.123';   
 SELECT DATENAME(year, @t);  
 ```  
   
 ## Remarks  
-DATENAME can be used in the select list, WHERE, HAVING, GROUP BY, and ORDER BY clauses.
+
+Use `DATENAME` in the following clauses:
+
++ GROUP BY
++ HAVING
++ ORDER BY
++ SELECT \<list>
++ WHERE
   
-In [!INCLUDE[ssCurrent](../../includes/sscurrent-md.md)], DATENAME implicitly casts string literals as a **datetime2** type. This means that DATENAME does not support the format YDM when the date is passed as a string. You must explicitly cast the string to a **datetime** or **smalldatetime** type to use the YDM format.
+In [!INCLUDE[ssCurrent](../../includes/sscurrent-md.md)], DATENAME implicitly casts string literals as a **datetime2** type. In other words, `DATENAME` does not support the format YDM when the date is passed as a string. You must explicitly cast the string to a **datetime** or **smalldatetime** type to use the YDM format.
   
 ## Examples  
-The following example returns the date parts for the specified date.
+This example returns the date parts for the specified date. Substitute a *datepart* value from the table for the `datepart` argument in the SELECT statement:
   
 `SELECT DATENAME(datepart,'2007-10-30 12:15:32.1234567 +05:10');`
   
@@ -141,7 +160,7 @@ The following example returns the date parts for the specified date.
   
 [!INCLUDE[ssSDWfull](../../includes/sssdwfull-md.md)] and [!INCLUDE[ssPDW](../../includes/sspdw-md.md)]
 
-The following example returns the date parts for the specified date.
+Thisexample returns the date parts for the specified date. Substitute a *datepart* value from the table for the `datepart` argument in the SELECT statement:
   
 ```sql
 SELECT DATENAME(datepart,'2007-10-30 12:15:32.1234567 +05:10');  
