Question

I would like to use sqlite (using Java JDBC, not sure if that matters) to add or replace a new row to a database, and return the autogenerated ID of the row, and I’m not sure how to do this efficiently/cleanly.

table definition has >= 3 columns:

• autogenerated integer ID
• unique key string (let’s call it key)
• other metadata

I can think of two general approaches:

1. SELECT ID FROM myTable WHERE key = ?
2. If there’s no match, INSERT a new row, and repeat step #1 to get the autogenerated ID

or

1. INSERT OR REPLACE INTO myTable (key, metadata) VALUES (?, ?)
2. SELECT ID FROM myTable WHERE key = ?

What should I do? Not sure if either approach is an atomic transaction. (well, the first isn’t, not sure about the 2nd)

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edit: I just tried the INSERT OR REPLACE approach, and it “works”, except that it also replaces the ID with a new one, which is not what I want to have happen. I want to keep the existing ID.

Answer 1

Using a PreparedStatement you can return the generated key for an insert so there is no need to run a select statement after a insert just to get the key.

To do this:

• When you prepare the statement, use
  the method that allows you specify it
  to return the generated keys.
• After you run the update call “getGeneratedKeys()” on the statement object.