How to select entries from second table that either do not have an entry or do not have a specific entry?
I'm trying to find entries in that either - do not have an entry at all - or do not have a specific entry Example: TABLE 1 Field A 100 101 102 TABLE 2 Field A. Field B 100 X 100. Y 100. Z 101. Y 101 Z The result should be: 101 102 Thanks a lot already!!!
(2.1) By Larry Brasfield (LarryBrasfield) on 2020-11-04 17:31:10 edited from 2.0 in reply to 1 [link] [source]
Either a join with suitable criteria, or the compound operator, "EXCEPT", will do that trick.
(3) By Larry Brasfield (LarryBrasfield) on 2020-11-04 18:31:37 in reply to 2.1 [link] [source]
create table One (A integer);
create table Two (A integer, B text);
insert into One values (100);
insert into One values (101);
insert into One values (102);
insert into Two values (100, 'X');
insert into Two values (100, 'Y');
insert into Two values (100, 'Z');
insert into Two values (101, 'Y');
insert into Two values (101, 'Z');
select A from One except select A from Two where Two.B in ('X');
Translated from the English description of how to solve the problem into SQL:
with cross as ( select A, B from ( select distinct A from one ), ( select distinct b from two ) ) select distinct a from ( select * from cross except select * from two ) ;
Of course, "coding" the SQL is quite simple and proletarian once one has defined the problem solution (what programmers do).