Hi,
I'd like to do something which I think should be quite easy - that is join 2 tables and create a new table.
Table A postcode_input has columns which include postcode, eastings, northings. there are 1,687,605 rows.
Table B bng_lat_long has columns lat, lon, e, n. There are 1,687,605 rows.
eastings = e and northings = n so there should be a 1 to 1 match. The eastings northings pair should be unique in aggregate.
So I tried doing this:
SELECT A.postcode, A.eastings, A.northings, B.lat, B.lon INTO postcode_lat_long
FROM postcode_input AS A
LEFT JOIN bng_lat_long AS B On A.eastings = B.e AND A.northings = B.n
And ended up with a table 13,708,233 rows long with what looks like plenty of duplicated rows. Some but not all are duplicated. What can I do to sort this out?
Thanks,
Andy
