How to find Similar rows?

Question

Dear All,
I have table with location data , which having around 2 million records, So performance is 
huge factor. Please see the table structure
sl
Street
City
Zip code
 state
Country
longitude
latitude
Mvalue
Logic 1
logic 2
Logic 3
1
2
3
4
5
6
I want do compare this location with  following logic...
  1) First comparing  street name , city ,zip ,state & country  
(  Update  logic1 as 1 
  2) by geographical co-ordinate  ( if distance between the location
 50 meter , update logic 2 as  1)
  3) Based on Mvalue ( if difference between the Mvalue
 less than  10% , update logic 3 as 
1)
-Sajid

Answer 1

Hello,
Did you compare records in the table by join another table, or you want to compare the adjacent rows in the same table with inner join or compare all rows with cross join?
Supposing that you want to compare the adjacent rows order by the "SL" column, You can refer to the following statement to update the column "logic1":
UPDATE compare
SET logic1= CASE
WHEN EXISTS(
SELECT 1 FROM compare c1 INNER JOIN compare c2 ON c1.sl=c2.cl-1
WHERE c1.street=c2.street AND c1.city=c2.city AND c1.[zip code]=c2.[zip code] AND c1.state=c2.state AND c1.country=c2.country)
THEN 1
ELSE NULL
END
If I have any misunderstanding, please post more details for further analysis.
Regards,
Fanny Liu
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Fanny Liu
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