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Can't solve the JPQL :parameter problem by using FUNC()

Ok, just to cut it short, I've done the actual JPQL without using any parameter first and it looks like this.
SELECT count(dt)
FROM transaction dt
WHERE dt.transactionType = 'TEST'
AND dt.date
BETWEEN FUNC('TO_DATE','01-2019','mm-yyyy')
AND FUNC('TO_DATE','02-2019','mm-yyyy')
This thing work! But the thing is now I need to make the transactionType and date as a parameter and this is how it looks like
SELECT count(dt)
FROM transaction dt
WHERE dt.transactionType = :transType
AND dt.date
BETWEEN FUNC('TO_DATE',:lastMonth,'mm-yyyy')
AND FUNC('TO_DATE',:nextMonth,'mm-yyyy')
So for :transType it's fine, but inside this FUNC() seems like I shouldnt put the parameter just like that and need some workaround. I've been googling and can't find any result.
The error was like this
You have attempted to set a parameter value using a name of
lastMonth,'mm-yyyy') that does not exist in the query string
As you can see, the parameter inside FUNC() take along the parameter behind it that meant for FUNC(). What did I miss? Enlighten me please.

Make sure you're using setString for the parameter type.
I always had difficulty with named parameters within JPA, depending upon how the query was created - try using ordinal parameters, eg: ?1 and set them by index.
I'd avoid FUNC as it can carry some major overhead if you're not extremely careful.

There's a workaround for this problem.
Initially, the simplified SQL as below:
SELECT count(*)
FROM table tb
WHERE tb.date between to_date('01-2020','mm-yyyy') and to_date('02-2020','mm-yyyy');
And by directly convert the simplified SQL to JPQL, it turns out as such:
SELECT count(tb)
FROM table tb
WHERE tb.date BETWEEN FUNC('TO_DATE','01-2020','mm-yyyy') AND FUNC('TO_DATE','02-2020','mm-yyyy')
But, the JPQL need to be dynamic as the date will not be static, so by using JPQL parameter to ensure this JPQL can be used at any date, instinctively I thought to use as such:
SELECT count(tb)
FROM table tb
WHERE tb.date BETWEEN FUNC('TO_DATE',:fromDate,'mm-yyyy') AND FUNC('TO_DATE',:toDate,'mm-yyyy')
But as my initial question when this thread first started, such JPQL will not work. So how did I found a workaround? Relatively quite simple actually.
Instead of using this to get the ranging date (as from sql wise I use to_date)
WHERE tb.date BETWEEN FUNC('TO_DATE','','') AND FUNC('TO_DATE','','')
I used this
WHERE FUNC('TO_CHAR','','') between (--fromDate) and (--toDate)
Which finally resulted in final working JPQL of
SELECT count(tb)
FROM table tb
WHERE FUNC('TO_CHAR',tb.date,'mm-yyyy') BETWEEN (:fromDate) AND (:toDate)

Use MySQL variables and assignments in hibernate

I have created the following query which is now in one of my java classes being used by Hibernate.
private static final String COUNT_INTERQUARTILE_SQL
= " SET #number_of_rows \\:= (SELECT COUNT(*) FROM carecube.visit)" +
" SET #quartile \\:= (ROUND(#number_of_rows*0.25))" +
" SET #medianquartile \\:= (ROUND(#number_of_rows*0.50))" +
" SET #sql_q1 \\:= (CONCAT('(SELECT 'Q1' AS quartile, visit.id FROM carecube.visit order by visit.id LIMIT 1 OFFSET ', #quartile, ')'))" +
" SET #sql \\:= (CONCAT_WS(' UNION ', #sql_q1, #sql_med))" +
" PREPARE stmt1 from #sql;" +
" EXECUTE stmt1;";`
The stack trace complains of a syntax errors for each line where I've set a mysql variable. Obviously it works in MySQL just fine.
I read that I can use double backslashes with assignments in Hibernate. This is the first time I've tried to use MySQL variables with Hibernate so am unsure if I'm missing anything out and whether 'PREPARE' and 'EXECUTE' are necessary?
Can someone with more knowledge point me where I am going wrong?
Also, where I am selecting Q1, I've placed that in single quotes, in MySQL workbench it is double quotes.
EDIT: I've added double quotes so hibernate doesn't throw a sissy fit with the assignments. I still can't for the life of me, figure out why I cannot just use '#sql' after i've prepared it.
EDIT: I receive the following error:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'PREPARE stmt1 from #sql_max; EXECUTE stmt1' at line 1
Thanks

I'm not sure if this is possible, but in my opinion this doesn't make much sense.
Some people have asked similar questions (they have some code samples in the answers if you want to check):
How to use Mysql variables with Hibernate?
How can I use MySQL assign operator(:=) in hibernate native query?
Hibernate is an ORM (Object Relational Mapping), so it's supposed to convert data between incompatible type systems (data from database) in objects. As far as I could understand your query, you're returning a COUNT, so it would be just one single result (row) and one single column, is that right?
Due the complexity of your query, I would say there are some options I could think of:
Use Criteria or HQL to run each query using Hibernate and then in Java work with the logic to have your desired result (may become much slower than the query in MySQL)
Create a VIEW with this SELECT (if possible), map it into an object as an #Entity and query directly to it
Create a FUNCTION/PROCEDURE (this is possible) and call it using CallableStatement
I like to think that the two elements here (Hibernate x Database) should have a well define responsibility in the project. First of all, I would try to use only Criteria/HQL for the queries (to use object properties), but if needed to use SQL I would keep all queries ANSI to allow interoperability. If it's not possible, I would create an object in the database to return what I want (view/procedure/function).
Mixing specific database provider code in the query, like your example, doesn't look a good practice.
If possible, I would definitely go for option 2. If it can't be done, surely for number 3.
Hope it's somehow helpful.

Numerical wildcard for jdbc prepareStatement?

I´m doing a query with a prepareStatement in JDBC. I would sometimes insert a "numerical woldcard" instead of an actual number.
Consider a query like this:
Domains: a int, b text;
pStatement =
dbConnection.prepareStatement("SELECT * FROM R1 WHERE a LIKE ? AND b LIKE ?");
Some times I would like to:
pStatement.setInt(1, 10);
pStatement.setString(2,"%");
pStatement.exequteQuery();
That is no problem, since the wildcard is a string.
Other times I would like to:
pStatement.setInt(1, ANY_INT_SHOULD_BE_VALID);
pStatement.setString(2, "Hello");
pStatement.exequteQuery();
That does not work. I could change the query and use i.e. "a <> 0" but that requires extra code and makes the use of a prepareStatement somewhat unnecessary.
Is there a way to solve this without changing the actual query, only the inserted values?

I could change the query and use i.e. "a <> 0"
For your requirement, this should be a IS NOT NULL.
but that requires extra code and makes the use of a prepareStatement somewhat unnecessary.
PreparedStatement is necessary for the VARCHAR column the most and that seems to be present in all scenarios.
pStatement.setString(2,"%");
This wouldn't match all the strings as LIKE operator is needed for % to take its special meaning.
Is there a way to solve this without changing the actual query, only the inserted values?
No, IMO, since the requirements are fundamentally different, you would need to have queries accordingly.

What does "=?" represent when used in an SQL query

I'm fairly new to SQL and I'm currently reworking a java program that another
programmer has developed. When I print one of his query select statements the script contains sql syntax:
SELECT * from database WHERE id = ?
I just want know what =? is supposed to do? I've been googling around and I can't find any relevant answer.

It's not a SQL notation, but a JDBC (Java Database Connectivity) notation. The ? gets replaced with a parameter that is specified separately. Using this approach, instead of trying to substitute the parameter yourself into the string, helps prevent the risk of SQL injection.

The ? is a place holder, a parameter, so that you can pass it in dynamically and return different results for different parameters.
Somewhere in the code you should see that he adds the parameter to the Statement object and execute it.

Most likely you are using a tool that will replace the "?" with an actual value. I've seen this in other tools before such as SQL DTS (Data Transformation Services)... but that's showing how old I am :)
The ? is not part of the SQL language.

The ? is a place holder used in SQL queries when used with JDBC Prepared statement. Using a prepared statement has advantages over the normal statement specially when you use it repeatedly (say in a loop).

Here is an example :
PreparedStatement ps =
connection.prepareStatement("select name from users where user_name = ?");
ps.setString(1, "user1");
the "?" gets replace by "user1" when the query is run and the first name of the user with user name "user1" is returned.

Is it possible to use GROUP BY with bind variables?

I want to issue a query like the following
select max(col1), f(:1, col2) from t group by f(:1, col2)
where :1 is a bind variable. Using PreparedStatement, if I say
connection.prepareStatement
("select max(col1), f(?, col2) from t group by f(?, col2)")
I get an error from the DBMS complaining that f(?, col2) is not a GROUP BY expression.
How does one normally solve this in JDBC?

I suggest re-writing the statement so that there is only one bind argument.
This approach is kind of ugly, but returns the result set:
select max(col1)
, f_col2
from (
select col1
, f(? ,col2) as f_col2
from t
)
group
by f_col2
This re-written statement has a reference to only a single bind argument, so now the DBMS sees the expressions in the GROUP BY clause and the SELECT list are identical.
HTH
[EDIT]
(I wish there were a prettier way, this is why I prefer the named bind argument approach that Oracle uses. With the Perl DBI driver, positional arguments are converted to named arguments in the statement actually sent to Oracle.)
I didn't see the problem at first, I didn't understand the original question. (Apparently, several other people missed it too.) But after running some test cases, it dawned on me what the problem was, what the question was working.
Let me see if I can state the problem: how to get two separate (positional) bind arguments to be treated (by the DBMS) as if it were two references to the same (named) bind argument.
The DBMS is expecting the expression in the GROUP BY to match the expression in the SELECT list. But the two expressions are considered DIFFERENT even when the expressions are identical, when the only difference is that each expression references a different bind variable. (We can demonstrate some test cases that at least some DBMS will allow, but there are more general cases that will raise an exception.)
At this point the short answer is, that's got me stumped. The suggestion I have (which may not be an actual answer to the original question) is to restructure the query.
[/EDIT]
I can provide more details if this approach doesn't work, or if you have some other problem figuring it out. Or if there's a problem with performance (I can see the optimizer choosing a different plan for the re-written query, even though it returns the specified result set. For further testing, we'd really need to know what DBMS, what driver, statistics, etc.)
EDIT (eight and a half years later)
Another attempt at a query rewrite. Again, the only solution I come up with is a query with one bind placeholder. This time, we stick it into an inline view that returns a single row, and join that to t. I can see what it's doing; I'm not sure how the Oracle optimizer will see this. We may want (or need) to do an explicit conversion e.g. TO_NUMBER(?) AS param, TO_DATE(?,'...') AS param, TO_CHAR(?) AS param, depending on the datatype of the bind parameter, and the datatype we want to be returned as from the view.)
This is how I would do it in MySQL. The original query in my answer does the join operation inside the inline view (MySQL derived table). And we want to avoid materializing a hughjass derived table if we can avoid it. Then again, MySQL would probably let the original query slide as long as sql_mode doesn't include ONLY_FULL_GROUP_BY. MySQL would also let us drop the FROM DUAL)
SELECT MAX(t.col1)
, f( v.param ,t.col2)
FROM t
CROSS
JOIN ( SELECT ? AS param FROM DUAL) v
GROUP
BY f( v.param ,t.col2)
According to the answer from MadusankaD, within the past eight years, Oracle has added support for reusing the same named bind parameters in the JDBC driver, and retaining equivalence. (I haven't tested that, but if that works now, then great.)

Even though you have issued a query through JDBC driver(using PreparedStatement) like this:
select max(col1), f(:1, col2) from t group by f(:1, col2)
At last JDBC driver replaces these like below query before parsing to the database , even though you have used the same binding variable name in the both places.
select max(col1), f(*:1*, col2) from t group by f(*:2*, col2)
But in oracle this will not be recognized as a valid group by clause.
And also normal JDBC driver doesn't support named bind variables.
For that you can use OraclePreparedStatement class for you connection. That means it is oracle JDBC. Then you can use named bind variables. It will solve your issue.
Starting from Oracle Database 10g JDBC drivers, bind by name is supported using the setXXXAtName methods.
http://docs.oracle.com/cd/E24693_01/java.11203/e16548/apxref.htm#autoId20

Did you try using ? rather than the named bind variables? As well, which driver are you using? I tried this trivial example using the thin driver, and it seemed to work fine:
PreparedStatement ps = con.prepareStatement("SELECT COUNT(*), TO_CHAR(SYSDATE, ?) FROM DUAL GROUP BY TO_CHAR(SYSDATE, ?)");
ps.setString(1, "YYYY");
ps.setString(2, "YYYY");
ps.executeQuery();

In the second case, there are actually two variables - you will need to send them both with the same value.