Below is an example of finding all the user who are stored in db and lies in the given range of Distance on basis of Longitude and Latitude.

CREATE proc [dbo].[SP_UserByDistance]
(
@UserID uniqueidentifier,--UserId
@Date datetime, --Date
@Longitude float, --Longitude of Location
@Latitude float, --Latitude of Location
@Distance float  --Distance in KM
)
as
Begin
SELECT * FROM
(
SELECT UCF.UserID,UCF.CategoryId,UCF.FlirtingNo AS FlirtingNo,Convert(nvarchar(11),UCF.DATE,101) AS Date,
       UCF.TIME AS Time,UCF.Longitude,UCF.Latitude,UCF.StateOfReg as Location,u.EmailID,u.ImagePath,
        3956 * 2 * ASIN(SQRT( POWER(SIN((UCF.Latitude - abs(@Latitude)) * pi()/180 / 2), 2) 
        + COS(UCF.Latitude * pi()/180 ) * COS(abs(@Latitude) * pi()/180)  
        * POWER(SIN((UCF.Longitude - @Longitude) * pi()/180 / 2), 2) )) 
        AS distance  FROM UserCategoryFlirting UCF 
        INNER JOIN  dbo.[User] AS U ON U.UserId = UCF.UserId 
 WHERE ucf.categoryid=3
 ) t

  WHERE distance <= @Distance and (cast(Date as Date) = cast(@Date as date) and UserID<>@UserID )

End


GO

Note:-Latitude Longitude of Users are save in UserCategoryFlirting table