Question

In Postgresql 8 why this is ok

select * from prod where code like '1%'
select * from prod where code like '%1'

but this returns 0 rows (there are codes begining/ending with digit 1)

select * from prod where code like '1%1'

Update

That happens in my current instalation:

# psql --version
psql (PostgreSQL) 8.3.7


create table a(code char(10));
CREATE TABLE
db=# insert into a values('111');
INSERT 0 1
db=# select * from a where code like '1%';
    code
------------
 111
(1 row)

db=# select * from a where code like '%1';
 code
------
(0 rows)

db=# select * from a where code like '1%1';
 code
------
(0 rows)

Update 2

It is the datatype ! With varchar it is Ok !

Thank you.

Answer 1

Is it because the datatype is char(10)?

This means that it will always occupy 10 characters even though you just insert something shorter like “111”. Therefore, if you don’t use a 10-characters string with “1” at the end, “%1” and “1%1” will never match.