Weird output for "INSERT INTO <VIEW with CHECK> (<FLD>) VALUES( <correct_value>) RETURNING <FLD>" // 3.x ... 6.x

[pavel-zotov]

Consider script:

set bail on;
set count on;
set heading off;
shell if exist r:\temp\tmp4test.fdb del r:\temp\tmp4test.fdb;
create database 'localhost:r:\temp\tmp4test.fdb' user 'sysdba' password 'masterkey';
 
recreate table t1 (id int generated by default as identity, n1 int, n2 int);
recreate view v1 as select t1.n1 from t1 t1 where t1.n1 < coalesce(t1.n2,100) with check option;
recreate view v2 as select t1.n1 from t1 t1;
 
insert into v1(n1) values(11) returning n1;
insert into v2(n1) values(12) returning n1;
select * from t1;
quit;

Current snapshots show following output:

1. on 3.x and 4.x:

insert into v1(n1) values(11) returning n1;

      <null>  -------------- [ 1 ] WHY ?

insert into v2(n1) values(12) returning n1;

          12 

select * from t1;

           1           11       <null> 
           2           12       <null> 

2. on 5.x and 6.x:

insert into v1(n1) values(11) returning n1;

           0   -------------- [ 2 ] WHY ??

insert into v2(n1) values(12) returning n1;

          12 

select * from t1;

           1           11       <null> 
           2           12       <null>