SQL - update main table using temp table

Question

I have a question about SQL, especially SQLite3. I have two tables, let's name them main_table and temp_table . These tables are based on the same relational schema so they have the same columns but different rows (values).

Now what I want to do:

For each row of the main_table I want to replace it if there is a row in a temp_table with the same ID. Otherwise I want to keep the old row in the table.

I was thinking about using some joins but it does not provides the thing I want.

Would you give me an advice?

EDIT: ADITIONAL INFO:

I would like to avoid writing all columns because those tables conains tens of attributes and since I have to update all columns it couldn't be necessary to write out all of them.

Answer 1

If the tables have the same structure, you can simply use SELECT * :

BEGIN;

DELETE FROM main_table
WHERE id IN (SELECT id
             FROM temp_table);

INSERT INTO main_table
SELECT * FROM temp_table;

COMMIT;

(This will also add any new rows in temp_table that did not previously exist in main_table .)

Answer 2

You have 2 approaches:

1. Update current rows inside main_table with data from temp_table . The relation will be based by ID.

2. Add a column to temp_table to mark all rows that have to be transferred to main_table or add aditional table to store IDs that have to be transferred. Then delete all rows that have to be transferred from table main_table and insert corresponding rows from temp_table using column with marks or new table.