How can I maintain the dateonly field
SQLite only supports some datatypes, and DATE is not one of them (https://sqlite.org/datatype3.html).

SQLite version 3.28.0 2019-04-16 19:49:53
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
sqlite&gt; CREATE TABLE `Checks` (`customerId` INTEGER NOT NULL NOT NULL, `checkDate` DATE);
sqlite&gt; insert into Checks values (1,1);
sqlite&gt; insert into Checks values (2,'08-09-2019');
sqlite&gt; insert into Checks values (3,'2019-09-08');
sqlite&gt; insert into Checks values (4,'eight september 2019');
sqlite&gt; insert into Checks values (5,'there is no checking if this really is a date!');
sqlite&gt; select * from checks;
1|1
2|08-09-2019
3|2019-09-08
4|eight september 2019
5|there is no checking if this really is a date!
sqlite&gt;