Oracle 18c

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drop table bad_design;
ORA-00942: table or view does not exist

create table bad_design
(
  beginn_datum varchar(12)
);
insert into bad_design values ('20200101');
1 rows affected

insert into bad_design values ('20220101');
1 rows affected

insert into bad_design values ('20220102');
1 rows affected

insert into bad_design values ('20220103');
1 rows affected

insert into bad_design values ('20220104');
1 rows affected

insert into bad_design values ('20220204');
1 rows affected

select *
from bad_design
WHERE BEGINN_DATUM BETWEEN to_number('20200101') AND 20220131;


BEGINN_DATUM


20200101

20220101

20220102

20220103

20220104


insert into bad_design values ('Gestern');
1 rows affected

select *
from bad_design
WHERE BEGINN_DATUM BETWEEN to_number('20200101') AND 20220131;
ORA-01722: invalid number