Re: What is the right syntax for retrieving the last_insert_id() in Postgresql ?

On Tue, 3 Mar 2020 at 16:50, Karen Goh <karenworld(at)yahoo(dot)com> wrote:

> Hi Pavel,
>
> Using this as reference and your link :
>
>
> https://dba.stackexchange.com/questions/3281/how-do-i-use-currval-in-postgresql-to-get-the-last-inserted-id
>
> I tried :
>
> select lastval('t_id') from table_tutor;
>
> but it is not working.
>
> Is there any tutorial out there that teaches the exact syntax ?
>
> Thanks & regards,
> Karen
> On Sunday, March 1, 2020, 06:27:00 PM GMT+8, Pavel Stehule <
> pavel(dot)stehule(at)gmail(dot)com> wrote:
>
>
>
>
> ne 1. 3. 2020 v 11:18 odesílatel Karen Goh <karenworld(at)yahoo(dot)com> napsal:
>
> Hi,
>
> I hope I am posting on the right forum. I googled but I can't find any
> solution pertaining to my problem.
>
> Could someone know what is the syntext for last_insert_id() in Postgresql
> for me to insert into my sql execute query?
>
>
> Postgres has not last_insert_id function. Maybe you think "lastval"
> function
>
> https://www.postgresql.org/docs/current/functions-sequence.html
>
> Regards
>
> Pavel
>
>
> public int getTutorById() {
> openConnection();
> int tutor_id = 0;
> try {
> Statement stmt3 = connection.createStatement();
> ResultSet rs = stmt3.executeQuery("SELECT
> last_insert_id() from xtutor");
> {
> while (rs.next()) {
> tutor_id = rs.getInt(1);
>
> }
> }
> } catch (SQLException e) {
> e.printStackTrace();
> }
> return tutor_id;
> }
>
> org.postgresql.util.PSQLException: ERROR: function last_insert_id() does
> not exist
> Hint: No function matches the given name and argument types. You might
> need to add explicit type casts.
> Position: 8
> at
> org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2440)
> at
> org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2183)
> at
> org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:308)
> at
> org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:441)
> at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:365)
> at
> org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:307)
> at
> org.postgresql.jdbc.PgStatement.executeCachedSql(PgStatement.java:293)
> at
> org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:270)
> at
> org.postgresql.jdbc.PgStatement.executeQuery(PgStatement.java:224)
> at daoMySql.tutorDAOImpl.getTutorById(tutorDAOImpl.java:202)
> at daoMySql.tutorDAOImpl.getAlltutors(tutorDAOImpl.java:161)
> at business.manager.getAlltutors(manager.java:99)
>
> The generated id is successfully generated by JDBC.
>
> The errors when I tested in out using PGAdmin4 is
>
> ERROR: function last_insert_id() does not exist
> LINE 1: SELECT last_insert_id() from xtutor;
> ^
> HINT: No function matches the given name and argument types. You might
> need to add explicit type casts.
> SQL state: 42883
> Character: 8
>
> Postgresql 11, Windows 11
>
> Thanks.
>
>
Hi,

Expanding a bit on John's answer, if you are using a serial or bigserial
field Postgres makes a sequence for that field.
For example:
create table xtutor(
t_id serial,
...
...

results a sequence named xtutor_t_id_seq(The schema is
tablename_fieldname_seq)

And when you check the table structure with \d xtutor you'll see something
like this:
Column | Type | Collation | Nullable |
Default
t_id | integer | | not null
| nextval('xtutor_t_id_seq'::regclass)

You can query the sequence as a table:

SELECT * FROM xtutor_t_id_seq;

or get the next value for a sequence(This advances the sequence as well):

SELECT nextval('xtutor_t_id_seq');

However...

Your example code looks like you are looking for the id of the most
recently inserted tutor in which case a better solution would be replacing
your select with this:
SELECT max(t_id) from xtutor;

Regards,
Sándor