Re: BUG #15971: Behaviour of SUBSTR function depending on its arguments

PG Bug reporting form schrieb am 21.08.2019 um 09:02:

> select substr('abcdef',1,2) val1, substr('abcdef',0,2) val2,
> substr('abcdef',-1,2) val3;
>
> The above query in Postgres returns expected result for val1 ('ab') but for
> val2 and val3, it returns 'a' and '' respectively. Oracle and most of other
> RDBMS systems would return 'ab' for val1 and val2.

The only "other" DBMS that behaves the way you describe it, is Oracle.

When I ran it on different systems, this is the result:

| val1 | val2 | val3 |
-----------|------|---------|---------|
Postgres | ab | a | <empty> |
SQL Server | ab | a | <empty> |
SQLite | ab | a | f |
MySQL | ab | <empty> | f |
Oracle | ab | ab | f |

DB2 and Firebird do not allow a starting position smaller than 1

So SQL Server works the same as Postgres and Oracle is the only one that returns 'ab' for the second case

So clearly the claim "most other" is wrong here.