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All Blog Articles, Data Models and Free Source Code by Simon Greener, The SpatialDB Advisor is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

COGO: DD2DMS Formatting a latitude/longitude decimal degree value

Friday May 06 2011 at 06:18

KeywordsSQL Server 2008 2012 DD2DMS decimal degrees formatted string
Summary

This article presents a function that takes a decimal degrees value and converts it to a formatted string. This function works for Sql Server 2008 and 2012.

Many years ago I had need to annotate the lines of a cadastral (land titles) polygon with the bearing and distance of each line. The bearings and distances need to be computed from the boundary of each land parcel. The annotation had to be formatted as DD^MM’SS.SS”. This was achieved with a function called DD2DMS which I have ported from PL/SQL (see my free COGO package) for use with SQL Server 2008 Spatial.

Note that I have a schema call cogo in which I create functions like this. You can use anything you like.

  1. /** ----------------------------------------------------------------------------------------
  2.   * @function   : DD2DMS
  3.   * @precis     : Function that takes a decimal latitude or longitude value and returns a formatted string.
  4.   * @version    : 1.0
  5.   * @usage      : Function DD2DMS(@p_dDecDeg       float,
  6.   *                               @p_sDegreeSymbol NVarChar(1) = NULL,
  7.   *                               @p_sMinuteSymbol NVarChar(1) = NULL,
  8.   *                               @p_sSecondSymbol NVarChar(1) = NULL )
  9.   *                RETURNS nvarchar(50)
  10.   *               eg select DD2DMS(45.5083333333333),'d','m','s')
  11.   * @param      : p_dDecDeg       : Non-NULL value in decimal degrees
  12.   * @paramType  : p_dDecDeg       : FLOAT
  13.   * @param      : p_sDegreeSymbol : Degree symbol, default is ^
  14.   * @param      : p_sDegreeSymbol : NVarChar(1)
  15.   * @param      : p_sMinuteSymbol : Degree symbol, default is '
  16.   * @param      : p_sMinuteSymbol : NVarChar(1)
  17.   * @param      : p_sSecondSymbol : Degree symbol, default is "
  18.   * @param      : p_sSecondSymbol : NVarChar(1)
  19.   * @return     : DMS String      : Formatted String.
  20.   * @returnType : DMS String      : NVarChar(50).
  21.   * @history    : Simon Greener - Apr 2007 - Original coding.
  22.   * @history    : Simon Greener - May 2011 - Ported to TSQL
  23.   * @copyright  : Licensed under a Creative Commons Attribution-Share Alike 2.5 Australia License.
  24.   *              (http://creativecommons.org/licenses/by-sa/2.5/au/)
  25. **/
  26. CREATE FUNCTION [cogo].[DD2DMS](@p_dDecDeg       FLOAT,
  27.                                 @p_sDegreeSymbol NVarChar(1) = NULL,
  28.                                 @p_sMinuteSymbol NVarChar(1) = NULL,
  29.                                 @p_sSecondSymbol NVarChar(1) = NULL )
  30. RETURNS nvarchar(50)
  31. AS
  32. BEGIN
  33.     DECLARE
  34.         @iDeg INT,
  35.         @iMin INT,
  36.         @dSec FLOAT,
  37.         @sDegSymbol NVARCHAR(1) = CASE WHEN @p_sDegreeSymbol IS NULL THEN '^'  ELSE @p_sDegreeSymbol END,
  38.         @sMinSymbol NVARCHAR(1) = CASE WHEN @p_sMinuteSymbol IS NULL THEN '''' ELSE @p_sMinuteSymbol END,
  39.         @sSecSymbol NVARCHAR(1) = CASE WHEN @p_sSecondSymbol IS NULL THEN '"'  ELSE @p_sSecondSymbol END;
  40.     BEGIN
  41.         SET @iDeg = CAST(@p_dDecDeg AS INT);
  42.         SET @iMin = CAST(((Abs(@p_dDecDeg) - Abs(@iDeg)) * 60) AS INT);
  43.         SET @dSec = Round((((Abs(@p_dDecDeg) - Abs(@iDeg)) * 60) - @iMin) * 60, 3);
  44.         RETURN STR(@iDeg,4,0) + @sDegSymbol + STR(@iMin,2,1) + @sMinSymbol + STR(@dSec,5,3) + @sSecSymbol;
  45.     END;
  46. END
  47. GO

Some test cases as examples.

  1. SELECT DD2DMS(NULL,NULL,NULL,NULL) AS DMS
  2. UNION
  3. SELECT DD2DMS(45.5083333333333,NULL,NULL,NULL)  AS DMS
  4. UNION
  5. SELECT DD2DMS(DMS2DD(-44,10,50),NULL,NULL,NULL) AS DMS
  6. UNION
  7. SELECT DD2DMS(DMS2DD(-44,10,50),'d','m','s') AS DMS;

Results

DMS
NULL
45^30’30.00”
-44^10’50.00”
-44d10m50.00s

I hope this is helpful to someone.

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