I have a table called
UC that has an email column, and I have a backup table of it.
I need to copy the data (emails) from the email column of the
backup table to the
uc table, but I don't know how to do this.
I made several attempts, without success. I had never encountered this situation, copying data between tables.
update uc set uc.email = backup.email from uc , backup where uc.idconsumidor = backup.idconsumidor;
UPDATE uc u SET (email) = (SELECT b.email FROM backup b WHERE u.idconsumidor = b.idconsumidor) WHERE EXISTS ( SELECT 1 FROM backup b2 WHERE u.idconsumidor = b2.idconsumidor)
The outside WHERE (the 2nd) exists to prevent you from updating records in table u that do not have matches in table backup . Without this where, unmatched records would have the email column set to NULL.