Hibernate HQL LEFT JOIN not performing same as equivalent SQL - java

Cannot work out why these two statements return a different number of results. They should be the same. The SQL version (correctly) returns 2 results and the HQL version returns (incorrectly) 3 results.
The output of the SQL returns 3 results of tb2.user with values 1, null and null. The where clause means this filters down to 2 results, removing the result with a tb2.user value of 1. However, the HQL version returns 3 results. I would like the HQL to return 2 results.
My SQL
SELECT * FROM table1 as tb1 LEFT JOIN table2 as tb2 ON tb1.user = tb2.blocked WHERE tb2.user <> 1 OR tb2.user is null;
My HQL
SELECT r FROM table1 tb1 LEFT JOIN table2 tb2 ON tb1.user.id = tb2.user.id WHERE tb2.user.id <> :userId OR tb2.user.id is null GROUP BY tb1
Any help on this is much appreciated!


You should not use left joined table's column in where condition .. this work as an inner join
you should move these condition in the related ON clause
and in the second query ( My HQL) you have an improper group by without aggregation function (so the query are not equivalent)
(when you need distinct result .. use Distinct clause )
SELECT r
FROM table1 tb1
LEFT JOIN table2 tb2 ON tb1.user.id = tb2.user.id
AND ( tb2.user.id <> :userId OR tb2.user.id is null )

Related

Optimizing a combination of update and select query using JAVA

I have one update query which I am updating using JAVA. It is connected to a Oracle SQL database. It is a combination of an update and select query.
Query: "Update table1 set col1 = 'true', col2= current_timestamp where table1.col1 <> 'true' and table1.col3 in (select col3 from table1 inner join table2 on table1.col3 = table2.col3 where table2.trdate is null or table2.trdate >= current_timestamp group by table1.col3 )
(select col3 from table1 inner join table2 on table1.col3 = table2.col3 where table2.trdate is null or table2.trdate >= current_timestamp group by table1.col3 ) -> Output of this query will be more 10 million rcords.
select table1.col3 where table1.col1 <> 'true' and table1.col3 in (select table1.col3 from table1 inner join table2 on table1.col3 = table2.col3 where table2.trdate is null or table2.trdate >= current_timestamp group by table1.col3 ) -> Output of this query will be around 30k rcords.
trdate is a timestamp.
col3 is a varchar and is connecting the two tables using join.
The above update query is taking lot of time (more than 6-7 hours) and is blocking the database.
Can someone suggest any better approach to optimize the query?
I am thinking to split the process into batches but since there are more than 10 million records, they will be using my space. Can someone help?

How to use Count(*) in JPQL

I have a JPQL subquery in which I want to return a list of customerIds that meet a specific condition based on a ManyToOne relationship as shown below:
SELECT c.customerId
FROM Customer c
INNER JOIN FETCH c.customersChild cc
LEFT JOIN FETCH c.childsPet cp on cp.name = 'Rover'
GROUP BY c.customerId
HAVING (COUNT(cp.name) / COUNT(*)) = 1
In this case, the customer should only be present in the list if all of their childrens' pet's names are Rover. The HAVING (COUNT(cp.name) / COUNT(*)) = 1 clause works as-is in Oracle (SQL), since COUNT(cp.name) counts the number of non-null rows for each customer, and COUNT(*) counts the total number of rows (including nulls present due to the left join) for each customer... I believe COUNT(cp.name) works in JPQL but it doesn't seem like there is equivalent for COUNT(*)... does anyone know if there is a way to count all the rows within a group including nulls?

I would suggest you rewrite your query to the more understandable anti-join variant:
SELECT c.customerId
FROM Customer c
WHERE NOT EXISTS (
SELECT 1
FROM c.customersChild cc
JOIN cc.childsPet cp
WHERE cp.name = 'Rover'
)

Oracle SQL query working in console but not working in HQL

I'm not sur why my SQL query works fine on Oracle console, but not with HQL.
Here's the query as I run it in my Oracle console :
select distinct table1.*
from TABLE1 table1, TABLE2 table2
where table1.ID in (
select max(table2.RID_TABLE2) from TABLE2 table2 group by RID_OBJECT
);
This query returns 5 rows, and for some reason, the exact same query in HQL returns 6 rows.
Here is the HQL query:
#Query(name = "select distinct table1.*
from TABLE1 table1, TABLE2 table2
where table1.ID in (
select max(table2.RID_TABLE2) from TABLE2 table2 group by RID_OBJECT
)")
Set<Object> findTable1ByTable2();
From what I've seen here, it might be related to the fact that I use a subquery in my where clause, and it seems like HQL queries do not allow it.
Basically, it seems like the following part of my 'where' my query is simply ignored with HQL table1.ID in (select max(table2.RID_TABLE2) from TABLE2 table2 group by RID_OBJECT).
My goal is to have both my SQL and HQL queries return 5 rows.
Is there a solution to this ?

Oracle SQL Developer - JOIN on 2 queries with a one-to-many relationship

I have two queries that I'm trying to join together.
In first_query TABLE2.PROCESS_ID, every PROCESS_ID is unique in that table. In second_query though there are several PROCESS_ID's with the same number in TABLE3, so I think I have to do a one-to-many join. The join_query I have is giving me an error ORA-00933: SQL command not properly ended which I'm assuming has something to do with the one-to-many relationship with the JOIN.
I'm not really sure how to resolve this. Any help would be much appreciated!
first_query = """
SELECT TABLE1.RULE_ID, TABLE2.STATUS, TABLE2.ERROR_MESSAGE, TABLE2.PROCESS_ID
FROM TABLE2 LEFT JOIN
TABLE1
ON TABLE1.RULE_ID = TABLE2.RULE_ID
WHERE TABLE1.RULE_NAME IN ('TEST1', 'TEST2')
"""
second_query = """
SELECT RECORDS_PROCESSED, PROCESS_ID, STATUS
FROM TABLE3
"""
join_query = """
SELECT RULE_ID, STATUS, ERROR_MESSAGE, PROCESS_ID
FROM (first_query) as query_1
INNER JOIN (second_query) as query_2
ON query_1.PROCESS_ID = query_2.PROCESS_ID
GROUP BY PROCESS_ID desc
"""

You can not select 4 columns and group by only one of them unles you include selected columns as part of aggregation fucntion(like max(), sum(),...). One of the options is this:
SELECT query_1.RULE_ID --1
, query_2.STATUS --2
, query_1.ERROR_MESSAGE --3
, query_1.PROCESS_ID --4
FROM (SELECT TABLE1.RULE_ID
, TABLE2.STATUS
, TABLE2.ERROR_MESSAGE
, TABLE2.PROCESS_ID
FROM TABLE2
LEFT JOIN TABLE1
ON TABLE1.RULE_ID = TABLE2.RULE_ID
WHERE TABLE1.RULE_NAME IN ('TEST1', 'TEST2')) query_1
INNER JOIN (SELECT RECORDS_PROCESSED
, PROCESS_ID
, STATUS
FROM TABLE3) query_2
ON query_1.PROCESS_ID = query_2.PROCESS_ID
GROUP BY query_1.RULE_ID
, query_2.STATUS
, query_1.ERROR_MESSAGE
, query_1.PROCESS_ID
Also please do consider using aliases like this(in your first query):
SELECT T1.RULE_ID
, T2.STATUS
, T2.ERROR_MESSAGE
, T2.PROCESS_ID
FROM TABLE2 T2
LEFT JOIN TABLE1 T1 ON T1.RULE_ID = T2.RULE_ID
WHERE T1.RULE_NAME IN ('TEST1', 'TEST2')
Also, apply the same logic with aliases on your final query or else you will have a different kind of error : "ORA-00918: column ambiguously defined"
Here is a small demo

CTE (i.e. the WITH factoring clause) might help.
WITH first_query
AS (SELECT table1.rule_id,
table2.status,
table2.error_message,
table2.process_id
FROM table2 LEFT JOIN table1 ON table1.rule_id = table2.rule_id
WHERE table1.rule_name IN ('TEST1', 'TEST2')),
second_query
AS (SELECT records_processed, process_id, status FROM table3)
SELECT a.rule_id,
a.status,
a.error_message,
a.process_id
FROM first_query a INNER JOIN second_query b ON a.process_id = b.process_id
GROUP BY you used is invalid; you can't group results by only one column. If results have to be unique, use select distinct. If you have to use group by, specify all columns returned by select (which leads you back to what distinct does), or see whether some column(s) have to be aggregates - in that case, group by makes sense.
Also, you should always use table aliases. Without them, query is invalid as database engine doesn't know which table those columns (if they share the same name) belong to.

Element collection returning odd query

I have an many to many table which I am querying and want to return one column from it
Consider
Table 1
M to M (consisting of TABLE1_ID and TABLE2_ID)
Table2
I am in Table 2 entity and I want to return all the table 2 ids in the M to M table when I give it a table 1 id.
In my entity I have
#ElementCollection
#CollectionTable(name="M_TO_M_TABLE", joinColumns=#JoinColumn(name="TABLE1_ID"))
#Column(name="TABLE_2_ID")
private Set<Integer> tableTwoIds;
When I try and query this the JPA query that is produced is weird!
My query is
SELECT tab2 from Table2 tab2 where tab2.tableOneIds in (:idsPassedIn)
The error I get makes sense from the query that is generated. The error is
org.hibernate.exception.GenericJDBCException: Missing IN or OUT parameter at index:: 1
and the query is
select tab2.ID, tab2.NOTES
from TABLE_2 tab2, M_TO_M mToM
where tab1.ID=mToM.TAB_1_ID and (. in (? , ?))
and we have a . after the and rather than mToM.TAB_2_ID
Has anyone any ideas?
Thanks

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