How to Retrieve Auto-Increment Values Before Insertion in MySQL/PHP?

Retrieving Auto-Increment Values before Insertion in MySQL/PHP

When uploading images to a storage server, it's often desirable to include the auto-increment value (e.g., 12345) in the filename. However, fetching this value before performing the insert can be a challenge.

Proposed Solution

One potential solution is to:

1. Insert an empty row into the table.
2. Retrieve the auto-increment value for the new row.
3. Delete the empty row.
4. Insert the actual data using the obtained auto-increment value.

Alternative Approach

A more commonly employed approach involves:

1. Inserting partial data into the table.
2. Retrieving the auto-increment value generated by the insertion.
3. Performing calculations based on the auto-increment value.
4. Updating the row with the final data, using the auto-increment value in the WHERE clause.

For added security, it's crucial to execute these operations within a transaction, ensuring that the process is either completed in its entirety or not executed at all.

Pseudo-Code

begin transaction
insert into your_table (partial_data);
$id = get last autoincrement id
do calculations
update your_table set data = full_data where id = $id
commit transaction

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