SQLite error: foreign key mismatch when I try to make an INSERT command

Apparently you dropped the object already. Now to calm you down - corrupted blocks now most probably are in free space and do no harm. They just annoy you during backups. To check that:

SELECT null owner, null segment_type, null segment_name, null partition_name, c.file#
  , greatest(f.block_id, c.block#) corr_start_block#
  , least(f.block_id+f.blocks-1, c.block#+c.blocks-1) corr_end_block#
  , least(f.block_id+f.blocks-1, c.block#+c.blocks-1)
  - greatest(f.block_id, c.block#) + 1 blocks_corrupted
  , 'Free Block' description
from dba_free_space f, v$database_block_corruption c
WHERE f.file_id = c.file# AND f.block_id <= c.block# + c.blocks - 1
  and f.block_id + f.blocks - 1 >= c.block#
order by file#, corr_start_block#;

If it really shows here you have two options. You can simply ignore it. Once the block will be assigned to some object it will be reformated and corruption will go away. If you want to fix corrupted blocks then you will have to create the object which would occupy your corrupted blocks.

Let's say your corrupted block exists in tablespace USERS and datafile /ora/users01.dbf. First you have to make datafiles of tablespace not autoextendable. That is not to inflate datafile size. And then you'll create filler table.

create table filler (
  padding varchar2(1000)
) tablespace users nologging pctfree 90 pctused 10;

Then you have to extend table's segment so that it would incorporate corrupt blocks:

alter table filler allocate extent
  (datafile '/ora/users01.dbf' size 100m);

In such way you can add several extents adjusting their sizes. After you'll check that corrupt blocks now longer belong to free space you can fill the table:

insert /*+append */ into filler  select rpad('x',1000) from
dba_objects
--  filler
where rownum <= 50000;

First insert/select goes from dba_objects then it is faster to insert/select from filler table itself.

Now you just have to check datafile using RMAN:

RMAN> BACKUP VALIDATE CHECK LOGICAL DATAFILE 333;

And drop filler table:

DROP TABLE filler PURGE;

Easy. :)

A simple CHECK constraint works just fine:

$ sqlite
SQLite version 3.8.4.1 2014-03-11 15:27:36
...
sqlite> CREATE TABLE table_B(
   ...>     user1,
   ...>     user2,
   ...>     [other stuff],
   ...>     CHECK (user2 < user1)
   ...> );
sqlite> INSERT INTO table_B VALUES (1, 0);
sqlite> INSERT INTO table_B VALUES (2, 3);
Error: CHECK constraint failed: table_B

(This has nothing to do with EAV.)