Re: Reset sequence to current maximum value of rows

On Thu, Jun 13, 2024 at 10:20 AM Rich Shepard <rshepard(at)appl-ecosys(dot)com>
wrote:

> Two tables have a sequence for the PK. Over time I manually entered the PK
> numbers not being aware of applying DEFAULT to generate the next number.
>
> I just tried to set one table's PK sequence to the current max(PK) value
> using this expression from a stackexchange thread:
> SELECT setval('<sequence_name>', <current_max_number>, true); -- next
> value will be max(PK) + 1
>
> Needing to add a new row to a table for a specific industry table (with 52
> rows) I set the PK as DEFAULT in the INSERT INTO expression. To my surprise
> and disappointment all 52 rows now have the company_name column as the
> newly
> inserted name. Feh! I need to restore all the correct names for each PK.
>

You need to show your work here. As your PK is a number it cannot have a
company name as a value and so this doesn't make sense.

> There's an alternate expression in that SE thread that I didn't try:
> ALTER SEQUENCE <sequence_name> RESTART WITH <next_number>;
>

This is identical in action to the setval function call you performed.

> I want to avoid this same situation when resetting the second table's PK
> sequence number and would like to understand why the SELECT expression
> changed all column values

It didn't...

> rather than adding a new row with its attributes.
>

It wouldn't do this either...

And how to I reset sequences to ignore all current values

This doesn't make sense...

while adding the
> next higher value to the end when a new row is INSERTed.
>
>
If you use the default when inserting the next value in the sequence is
used.

David J.