MYSQL Maria DB-比较2个表A和B并更新记录

Question

I have 2 tables A and B. I wanted to compare table A with table B and for any mismatched record I wanted to update the entire record from table A to Table B. We have 2 primary keys and have around 40 million records.

Can we achieve this in one SQL or Script? Or can I create temporary table(Table c) where I can write table A records which are mismatching and then update Table B with temporary Table C. This I would be doing in MY SQL workbench and using mariaDB DB.

Added additional information - I have 2 primary keys and 15 columns. So, Ideally have to match 13 columns and find mismatches assuming the primary key matches in both tables.

Please assist and appreciate for any feedback.

Answer 1

One approach is to do an update left join of the B table to the A table, and update all columns in the former table with values from the latter. Note that the WHERE clause checks to make sure that a record in B did not match to any record in A.

UPDATE TABLE_B b
LEFT JOIN TABLE_A a
    ON a.col1 = b.col1 AND
       a.col2 = b.col2     -- AND all other columns
SET b.col1 = a.col1,
    b.col2 = a.col2        -- AND set all other columns
WHERE a.col1 IS NULL