Question about like

Merry Christmas and hello everybody

I have a test table with a field called 'name' which have three
entries:
Johanna
Karl
Uwe

If I query this table with
- select name from test where name like 'Uwe';
- select name from test where name like 'U_e';
- select name from test where name like '%e';
or
- select name from test where name like '---';

in all cases pg responds with 0 rows found.

I was expecting another result;-(
Does anybody have a hint or an explanation for this behaviour?
My system is RedHat 7.1 with PostgreSQL 7.1.3

Many thanks
Conni