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How to query a boolean column using an integer with Postgres?

I post a similar question previously, but have opened another question to be more specific as the previous one gave me a solution but I have now encountered another problem.
We have an existing Oracle database that had boolean columns defined like so
CREATE TABLE MY_TABLE
(
SOME_TABLE_COLUMN NUMBER(1) DEFAULT 0 NOT NULL,
etc..
And with the corresponding java field defined like private boolean someTableColumn; I've come to understand this is because Oracle does not have a Boolean datatype, but under the hood does the conversion from boolean to integer when inserting data, and the reverse when retriving data.
This has caused an issue when I have been working on migrating our database from Oracle to Postgres. Thanks to answers on my previous question, I have migrated the column type from NUMBER(1) to BOOLEAN. This has solved the issue with inserting data. However, our codebase uses JDBCTemplate and we unfortunately have hundereds of hardcoded queries in the code that make queries like SELECT * FROM MY_TABLE WHERE TABLE_COLUMN=1.
When these run against the Postgres DB, I get the following error ERROR: operator does not exist: boolean = integer. We have a requirement to have backwards compatability with Oracle, so I can't simply update these queries to replace 1 and 0 with TRUE and FALSE respectively.
Is there a way I can configure Postgres so it can do a conversion behind the scenes to resolve this? I have looked at casts but I don't really understand the documentation and the examples given don't seem to match my use case. Any help is appreciated.

Can you try to use '0' and '1' instead of 0 and 1 in your requests ?
I used to work on apps compliant with both Oracle and Postgresql using this syntax. Apps were using JPA but can say with certainty that we were also using this syntax with nativeQuery = true.
Note: I would have posted this as a comment but I don't have the required reputation to do so, hence the post as an answer

Update:
Duh! Brain Freeze. On later thought there is a way to get this conversion in both directions. Process via a View.
Steps:
Rename your table.
Create a view having the same name as the old table. In this view
translate the boolean column to the appropriate integer.
Create an trigger function and an instead of trigger on the view for insert/update dml. In the trigger function translate the column value to boolean as appropriate.
See revised demo.
alter table testb rename to testb_tab;
create or replace view testb (id, name, is_ok)
as
select i,
, name
, is_ok::int
from testb_tab;
create or replace
function testb_act_dml()
returns trigger
language plpgsql
as $$
begin
if tg_op = 'INSERT' then
insert into testb_tab(name,is_ok)
values (new.name, new.is_ok::boolean) ;
else
update testb_tab
set name = new.name
, is_ok = new.is_ok::boolean
where id = old.id;
end if;
return new;
end;
$$;
create trigger testb_biuri -- before insert update row instead of
instead of insert or update on testb
for each row execute function testb_act_dml();
Finally, there is another option which probably has the lease work. Do not change the column description to Boolean. Either leave it as an integer or define it as a smallint. Either way a check constraint may come in useful. So something along the line of:
create table tests( id int generated always as identity primary key
, name text
, is_ok smallint
, constraint is_ok_ck
check ( is_ok in (0,1) or is_ok is null)
);
This is one of the issues I have with the concept of "database independence". It simply does not exist. Vendors implementation often simply vary too much. In this case Postures to the rescue, perhaps but also perhaps extreme: create you own create your own operators. Proceed with caution:
-- function to compare boolean = integer
create or replace
function"__bool=int"( b boolean, i int)
returns boolean
language sql
as $$
select (b=i::boolean);
$$;
-- create the Operator for boolean = integer
create operator = (
leftarg = boolean
, rightarg = int
, function = "__bool=int"
, commutator = =
);
The above will not allow your code: SELECT * FROM MY_TABLE WHERE TABLE_COLUMN=1 (see demo here).
However, this road may lead to unexpected twists, and lots of function/operator pairs. For example the above does not support SELECT * FROM MY_TABLE WHERE TABLE_COLUMN<>1. That requires another function/operator combination. Further I do not see a retrieval function that converts a boolean back to an integer. If you follow this path be sure to massively test your boolean-to-integer (integer-to-boolean) operations. It may just be better to just byte the bullet and updated those few queries (you did say hundreds not thousands) as #mlogario suggests.

how can i implement haskey() function with a query in mysql

I'm translating a program form python to java and I'm working with mysql
at some point I have to check in my db if I have data with a special key.
let's say
if(namesTable.haskey(24))
doSoemthing();
I don't need any retrieved data from db I just want to see if there is anything with this special key or not. Additionally, I dont want to use COUNT because using count means to go through all the db and give me a number like 248 while I just care if there is any or not.
I want something to give me a yes as soon as it finds a match in database.

(I interpreted the "check in my db if I have data with a special key" to mean that you are checking a single column in a single table for the existence of a particular value. That seems to be the most straightforward interpretation.)
If you need to check a table to see if a row exists in a particular table, with a particular value in a particular column, the most efficient query might be:
SELECT 1
FROM DUAL
WHERE EXISTS (SELECT 1
FROM mytable t
WHERE t.key = 24
)
The pseudo table DUAL is guaranteed to return no more than one row, and the EXISTS subquery will "exit" with TRUE as soon as one row is found.
For best performance, you'll want an index with key as the leading column, e.g.
ON mytable (key)

I would recommend to use a flag in your application, like:
Boolean hasKey = false;
On startup of your program, you need to run the sql query against namesTable just once to check if it has the special key and on the basis of that query result set the hasKey. From then and onwards you don't need to check the db again, and you can simply use:
if(hasKey)
{
soSomething();
}
On add/update of a record in namesTable, check if it has special key, if yes then set the hasKey flag to true.

Create new table entry with new id

The problem
I have a table for some data that has an ID column of type integer (which is also the primary key).
When a new data entry is added to the table, it should get a new ID whereas the ID is not known by the application that inserts the object but it should be given by the database. For example, the IDs should be assigned like 0, 1, 2, ...
Assume that I have all other data for the new entry, how would I do the insert? Normally:
insert into T values(123, 'data');
But now I don't know what to put instead of 123
- would you create some kind of global variable NEXTID in the database that provides the IDs and query/update this value each time before inserting into T?
The questions
How to handle this kind of problem? A solution that is concurrency save is preferable.
How to achieve this with Java/myBatis? I Have a Java class that corresponds to the table structure and a new object should be added to the database, getting a new ID automatically.
Update
What I searched for was auto-increment.
Is there a standard SQL way (database independent) of declaring a column as auto-increment? I am using Apache Derby and GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1) is suggested here.
How does the insert to a table that contains auto-increment columns look like?
What is the best way to get the created auto-increment value after an insert when simultaneaous access to the database is possible?
I'll accept an answer that includes explanation and SQL instructions for declaration and insertion :)

If you are using sqlserver, making column of identity type will solve the purpose something like this
.
ALTER TABLE [dbo].[T] ADD [Column1] INT identity (1, 1)
For others like oracle you can for simple database sequence.

In MySQL you can use
ALTER TABLE table_name ADD id INT AUTO_INCREMENT;
this auto increment the id column, you don't have to give in insert.

Get Sequence Name (Oracle)?

I don't have access to see the database, but I have the ability to create database objects (via an xml file). The xml documentation says that if I set an attribute called "identity" to true then a sequence will be created. Is it possible for me to write logic that would return the name of the sequence so that I can use nextVal when I'm writing INSERT statements?
Robert
Here's the documentation, do a find on the word "identity"...

If you can run select statements, then you might be able to try select * from user_sequences to get the names of sequences. Otherwise, could you please send the documentation for this database creation utility that you are using, if it is public. Otherwise, it will be very difficult to answer this question.
EDIT:
After a review of the documentation, it said that if you created a table with a primary key, it would create a sequence with the following rules, quoted directly from the documentation:
Primary keys must contain one columnref subelement that includes a single attribute, name, that references the column name to include in the primary key. In SQL Server, the key is mapped as an identity field with an auto-incremented value. On Oracle, a sequence is automatically created with the table name plus _seq suffix.
Thus, your query would be:
select * from all_sequences where sequence_name = upper(tablename || '_SEQ');

dictionary data insert or select (oracle, java)

I have an table (in ORADB) containing two columns: VARCHAR unique key and NUMBER unique key generated from an sequence.
I need my Java code to constantly (and in parallel) add records to this column whenever a new VARCHAR key it gets, returning the newly generated NUMBER key. Or returns the existing NUMBER key when it gets an existing VARCHAR (it doesn't insert it then, that would throw an exception of course due to the uniq key violation).
Such procedure would be executed from many (Java) clients working in parallel.
Hope my English is understandable :)
What is the best (maybe using PL/SQL block instead of Java code...) way to do it?

I do not think you can do better than
SELECT the_number FROM the_table where the_key = :key
if found, return it
if not found, INSERT INTO the_table SELECT :key, the_seq.NEXT_VAL RETURNING the_number INTO :number and COMMIT
this could raise a ORA-00001(duplicate primary key insert)
if the timing is unlucky. In this case, SELECT again.
Not sure if JDBC supports RETURNING, so you might need to wrap it into a stored procedure (also saves database roundtrips).
You can use an index-organized table (with the_key as primary key), makes the lookup faster.