Why Hibernate HSQL Concat is not working for MSSQL? - sql-server

Question

So, I have Hibernate 5.3.1 in a project which connects to different enginees (MySql, Oracle, PostgreSQL and MS SQL), so I can't use native queries.
Let's say I have 3 records in a table, which all of them have the same datetime, but I need to group them only by date (not time). For example, 2019-12-04;
I execute this query:
SELECT
CONCAT(year(tx.date_), month(tx.date_), day(tx.date_)),
iss.code,
COUNT(tx.id)
FROM
tx_ tx
JOIN
issuer_ iss
ON
tx.id_issuer = iss.id
GROUP BY
CONCAT(year(tx.date_), month(tx.date_), day(tx.date_)), iss.code
But, when I test it connected to SQL SERVER 2017, instead of return 20191204, it's returning 2035. In Oracle and MySQL is working fine.
Anyone has any idea why is this happen? I've tried different ways, like use + instead of CONCAT but the result is the same.
I've also tried to extract them for separate (without concat), and they have been returning correct. The problem is, I need to group them by the complete date.
And just for the record, the field is declared as datetime2 in DDBB

Answer 1

How about simply adding them, instead of using CONCAT.
(year(tx.date_)*10000 + month(tx.date_)*100 + day(tx.date_)*1) AS datenum
Thus, try this:
SELECT
CAST((year(tx.date_)*10000 + month(tx.date_)*100 + day(tx.date_)*1) AS string) AS datenum,
iss.code
FROM tx_ tx
JOIN issuer_ iss
ON tx.id_issuer = iss.id
GROUP BY year(tx.date_), month(tx.date_), day(tx.date_), iss.code

Answer 2

Thanks for the hint Gert Arnold gave me. I just didn't realize that the query was adding like if they were numbers in MSSQL.
Finally, I manage to make it work in the 4 RDBMS casting to string first
SELECT
CONCAT(CAST(year(tx.date_) AS string), CAST(month(tx.date_) AS string), CAST(day(tx.date_) AS string)),
iss.code
FROM
tx_ tx
JOIN
issuer_ iss
ON
tx.id_issuer = iss.id
GROUP BY
CONCAT(year(tx.date_), month(tx.date_), day(tx.date_)), iss.code
I tried also casting to TEXT, but it throws exception in MySQL

Answer 3

Why use concat() to begin with?
Assuming Hibernate takes care of converting the non-standard year(), month() and day() functions, then the following should work on any DBMS
SELECT year(tx.date_), month(tx.date_), day(tx.date_), iss.code
FROM tx_ tx
JOIN issuer_ iss ON tx.id_issuer = iss.id
GROUP BY year(tx.date_), month(tx.date_), day(tx.date_), iss.code