[FEATURE] Add name convention links and udf_CalculateDistanceBetween2Coordinates

Author: ktaranov

SQL Server Name Convention and T-SQL Programming Style.md

@@ -2,9 +2,10 @@
 
 Official Reference and useful links
  - [Transact-SQL Formatting Standards](https://www.simple-talk.com/sql/t-sql-programming/transact-sql-formatting-standards-%28coding-styles%29/) (by Robert Sheldon)
+ - [Subjectivity : Naming Standards](http://blogs.sqlsentry.com/aaronbertrand/subjectivity-naming-standards/) (by Aaron Bertrand)
  - [General Database Conventions](http://kejser.org/database-naming-conventions/general-database-conventions/) (by Thomas Kejser)
- - [Writing Readable SQL](http://www.codeproject.com/Articles/126380/Writing-Readable-SQL)
- - [SQL Style Guide](http://www.sqlstyle.guide/) (Simon Holywell)
+ - [Writing Readable SQL](http://www.codeproject.com/Articles/126380/Writing-Readable-SQL) (by Red Gate_)
+ - [SQL Style Guide](http://www.sqlstyle.guide/) (by Simon Holywell)
  - [SQL Code Layout and Beautification](https://www.simple-talk.com/sql/t-sql-programming/sql-code-layout-and-beautification/) (by William Brewer)
  - [TSQL Coding Style](http://www.databasejournal.com/features/mssql/tsql-coding-style.html) (by Gregory Larsen)
  - [Database object Limitations](http://technet.microsoft.com/en-us/library/ms172451%28v=sql.110%29.aspx)

User_Defined_Function/udf_CalculateDistanceBetween2Coordinates.sql

@@ -0,0 +1,61 @@
+IF OBJECT_ID('dbo.udf_CalculateDistanceBetween2Coordinates', 'FN') IS NULL
+EXECUTE ('CREATE FUNCTION dbo.udf_CalculateDistanceBetween2Coordinates() RETURNS INT AS BEGIN RETURN 1 END;');
+GO
+
+CREATE FUNCTION dbo.udf_CalculateDistanceBetween2Coordinates
+(
+      @Lat1  Float(18),
+      @Long1 Float(18),
+      @Lat2  Float(18),
+      @Long2 Float(18),
+      @ReturnType VarChar(10)
+)
+
+Returns Float(18)
+
+AS
+/*
+Note
+    Author: Vignesh Arulmani
+    Original link: http://www.sqlservercentral.com/scripts/Calculate+Distance/118083/
+Examples
+    select dbo.udf_CalculateDistanceBetween2Coordinates('37.7749300 ','-122.4194200','34.0522222','-118.2427778','Miles');
+    select dbo.udf_CalculateDistanceBetween2Coordinates('37.7749300 ','-122.4194200','34.0522222','-118.2427778','Kilometers');
+    select dbo.udf_CalculateDistanceBetween2Coordinates('37.7749300 ','-122.4194200','34.0522222','-118.2427778','Meters');
+    select dbo.udf_CalculateDistanceBetween2Coordinates('37.7749300 ','-122.4194200','34.0522222','-118.2427778','Feet');
+*/
+Begin
+
+  Declare @R Float(8);
+  Declare @dLat Float(18);
+  Declare @dLon Float(18);
+  Declare @a Float(18);
+  Declare @c Float(18);
+  Declare @d Float(18);
+
+  Set @R = 
+        Case @ReturnType
+        When 'Miles' Then 3956.55 
+        When 'Kilometers' Then 6367.45
+        When 'Feet' Then 20890584
+        When 'Meters' Then 6367450
+        Else 20890584
+        End
+
+  Set @dLat = Radians(@lat2 - @lat1);
+
+  Set @dLon = Radians(@long2 - @long1);
+
+  Set @a = Sin(@dLat / 2)
+             * Sin(@dLat / 2)
+             + Cos(Radians(@lat1))
+             * Cos(Radians(@lat2))
+             * Sin(@dLon / 2)
+             * Sin(@dLon / 2);
+  Set @c = 2 * Atn2(sqrt(@a),sqrt(1-@a));
+
+  Set @d = @R * @c;
+  Return @d;
+
+End;
+Go