I have a stored procedure which calculates the distance between 2 coordinate points:

CREATE PROC loc.CalcDistanceByPostalCode ( @From VARCHAR(10), @To VARCHAR(10) ) AS BEGIN     DECLARE @data table(From_Place VARCHAR(200), From_Region VARCHAR(200), "To_Place" VARCHAR(200), To_Region VARCHAR(200), Distance decimal(8,2))     DECLARE @postal1 table(ID int IDENTITY(1,1), place_name VARCHAR(200), region_name VARCHAR(200), latitude decimal(12,9), longitude decimal(12,9))     DECLARE @postal2 table(ID int IDENTITY(1,1), place_name VARCHAR(200), region_name VARCHAR(200), latitude decimal(12,9), longitude decimal(12,9))       INSERT INTO @postal1 SELECT distinct l.place_name, l.region_name, l.latitude, l.longitude from loc.locations l cross join loc.locations_postal lp where postal_code like @From and lp.city_id = l.ID     INSERT INTO @postal2 SELECT distinct l.place_name, l.region_name, l.latitude, l.longitude from loc.locations l cross join loc.locations_postal lp where postal_code like @To and lp.city_id = l.ID      INSERT INTO @data      SELECT         t1.place_name,  t1.region_name, t2.place_name, t2.region_name,         loc.FN_CalcAerialDistance(t1.latitude, t1.longitude, t2.latitude, t2.longitude) -- Function calculates Distance     FROM @postal1 as t1     CROSS JOIN @postal2 as t2     WHERE t1.latitude <> t2.latitude and t1.longitude <> t2.longitude      DECLARE @Distance decimal(8,2) = 0     select * from @data order by Distance desc     SELECT @Distance = Distance from @data     return @Distance; END 

It calculates correct result if @From and @To are different, but gives redundant data if @From and @To are same.

Example: Different @From and @To:

EXEC loc.CalcDistanceByPostalCode @From = '110%', @To = '400%'` 

Result:

From_Place  From_Region To_Place     To_Region      Distance Delhi       Delhi        Mumbai      Maharashtra    1160.65 New Delhi   Delhi        Mumbai      Maharashtra    1157.80 Delhi       Delhi        Vasai-Virar Maharashtra    1115.68 New Delhi   Delhi        Vasai-Virar Maharashtra    1112.87 

Example: Same @From and @To:

EXEC loc.CalcDistanceByPostalCode @From = '110%', @To = '110%'` 

Result:

From_Place  From_Region To_Place    To_Region   Distance New Delhi   Delhi       Delhi       Delhi       3.51 Delhi       Delhi       New Delhi   Delhi       3.51 

Do I need to write extra code to check if Distance is same then compare the From_Place with To_Place with the rows having the same distance? or any optimised way to prevent the duplicate data?