I am starting out at Hibernate. I am at the point, where I try out SQL in HQL.
I saw a code example which I wanted to recreate, but my output ended up being different.
To use SQL in HQL, that person said, if you want to only use a couple of columns, you need to use a Map to get certain columns (So I can´t simply use addEntity here).
My Student table got sId, sName, sMarks. Now I want to retrieve only the Students names (sName) and their marks (sMarks).
The Problem is, that I only get "null" as values for the names and marks whilst the object shows me the proper values:
Console Output:
Hibernate: SELECT sName,sMarks FROM student
{SNAME=Nameless fool number 1, SMARKS=65}
null : null
The Code:
NativeQuery querySQL2 = session.createNativeQuery("SELECT sName,sMarks "
+ "FROM student");
querySQL2.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP);
List students = querySQL2.getResultList();
for (Object o : students)
{
System.out.println(o);
Map m = (Map)o;
System.out.println(m.get("sName") + " : " + m.get("sMarks"));
}
Why do I get the proper Object with Syso(o) and just null with Syso(m.get("..."))?
Thank you in advance!
Actually you already answered your question
{SNAME=Nameless fool number 1, SMARKS=65}. Hibernate convert column names to upper case.
Related
Let's suppose I have a table: Person(Name: univarchar) and this table contains a row "abc".
I search Person by using Hibernate (Criteria API and HQL):
Criteria API:
Criteria c = session.createCriteria(Person.class);
c.add(Restrictions.ilike(name,"abc"));
return c.list();
HQL:
String query = "from Person where lower(name) like :name";
Query q = session.createQuery(query);
query.setString("name","abc");
return query.list();
It return empty result. However, when I use Interactive SQL of Sybase to execute SQL statement that is generated by Hibernate, it return a row "abc".
I found a solution for HQL case. This is to use rtrim function:
String query = "from Person where lower(rtrim(name)) like :name";
...
But my problem is I want to use Criteria API and I cannot find any ways to trim name column by using Criteria API.
Thanks and sorry for my poor English.
Have you tried with this code :
Criteria c = session.createCriteria(Person.class);
c.add(Restrictions.ilike(name,"abc",MatchMode.ANYWHERE));
return c.list();
If this will not work then Read this. Its similar Just he wants to trim while Order you want to trim while Restrictions.
I am using Postgres 9.3.2 to make a database of contacts.
Example: If i have a row in my table that looks something like this.
{
firstName : "First name"
lastName : "Last name"
emails : ["email#one.com", "email#two.com", "email#three.com]
}
PS: firstName, lastName and emails are columns in my db and the value associated is the value for that column for that specific row.
I want to be able to query the db so that if i query for the email "email#four.com" the result is nothing but if i query for "email#two.com" the result will be the above row entry.
I dont think the query
"Select * from contactTable where emails="email#two.com""
will work. instead i want to do something like
"Select * from contactTable where emails contains "email#two.com""
any ideas on how to do this?
"Select * from contactTable where emails contains "email#two.com""
I think you want:
"Select * from contactTable where thejsonfield -> emails
Example setup, after fixing up your totally broken json:
CREATE TABLE contacts AS SELECT '{
"firstName" : "First name",
"lastName" : "Last name",
"emails" : ["email#one.com", "email#two.com", "email#three.com"]
}'::json AS myjsonfield;
The following will work in PostgreSQL 9.4, but unfortunately does not in 9.3 due to the oversight of the missing json_array_elements_text function:
select *
from contacts,
lateral json_array_elements_text(myjsonfield -> 'emails') email
where email = 'email#two.com';
For 9.3, you have to use a clumsier method to scan the json array for matching values:
select *
from contacts,
lateral json_array_length(myjsonfield -> 'emails') numemails,
lateral generate_series(0, numemails) n
WHERE json_array_element_text(myjsonfield -> 'emails', n) = 'email#two.com';
You can't use the simple IN or = ANY constructs because (at this point) PostgreSQL doesn't understand that you might have a json array, so it'll fail with:
regress=> SELECT * FROM contacts WHERE 'email#two.com' = ANY (myjsonfield->'emails');
ERROR: op ANY/ALL (array) requires array on right side
LINE 1: SELECT * FROM contacts WHERE 'email#two.com' = ANY (myjsonfi...
^
as it expects a PostgreSQL array, not a json array, and there's no convenient builtin to turn a json array into a PostgreSQL array yet.
Postgres has support for parsing JSON. Here is documentation: http://www.postgresql.org/docs/9.3/static/functions-json.html. I can't give you more detailed answer since you didn't provide exact data and schema, but it's easy to find the right function in documentation.
I'm a newbie at Hibernate so excuse me if some of this is glaringly obvious but it's been a very, very long day. I am trying to create and execute a simple query in Hibernate and Toad/Oracle.
The Toad/Oracle sql reads:
select
count(*)
from
fpps_owner.fee_claim_payment_lines l,
fpps_owner.fee_claim_payments p
where
l.fee_claim_payment_id = p.fee_claim_payment_id and
p.claim_index = 87167895
The above returns 10 records, which is correct
The following Java code returns 0 records, which is NOT correct
String sLinesAvailable =
"select count(*) from " +
"fpps_owner.fee_claim_payment_lines l, fpps_owner.fee_claim_payments p " +
"where " +
"l.fee_claim_payment_id = p.fee_claim_payment_id and p.claim_index = :id";
Query qLinesAvailable = em.createNativeQuery(sLinesAvailable);
qLinesAvailable.setParameter("id", "87167895"); // fails
qLinesAvailable.setParameter("id", 87167895); // fails
List<Object> out = (List<Object>) qLinesAvailable.getResultList();
BigDecimal x = (BigDecimal) out.get(0);
Returns 0 records. Using .getSingleResult() also returns 0 records.
What am I missing here?
Any help would be GREATLY appreciated!
If you are not seeing any malformed query errors, it seems like the parameter is not binding correctly.
To debug, I'd print out that SQL statement the line after you set the parameter. This is the only way you can see the SQL after the parameter is set in order to compare it with Toad.
What does your binding file look like? Maybe you have a different name in there for the ID, so it's not able to find it based on the name. Trying binding with the parameter's order value, just as a test.
This might give some ideas: http://www.mkyong.com/hibernate/hibernate-parameter-binding-examples/
Best of luck! We've all been there :)
What happens when you try:
(Number) query.getSingleResult();
Your query isn't returning a list, but rather just a count.
Good luck.
I have been trying out some LINQ query can someone please show how to convert the following SQL query to LINQ:
SELECT *, firstname+' '+lastname AS FullName FROM Client WHERE age > 25;
Don't worry about the where part (put it in for completeness) more wandering how to achieve that first part.
Now I have come across something like this:
from c in dc.Clients select new {FullName = c.firstname + " "+c.lastname}
But i don't know how to get it to select everything else without specifying it ie:
{firstname = c.firstname, id = c.id ..... etc}
But I was hoping for another way of achieving that.
So I'm just wandering if someone could show me the right or another way of accomplishing this :)
Thanks All :)
You have to select the actual item then refer to its properties. There's no way to expand the individual columns into the anonymous type.
var query = from c in dc.Clients
where c.Age > 25
select new
{
Client = c,
FullName = c.firstname + " " + c.lastname
};
foreach (var item in query)
{
// item.Client.Id
// item.FullName
// item.Client.FirstName
}
Selecting the actual item gives you access to the same properties you were using to construct the anonymous type. It's not a complete waste though if the query had more going on, such as a join with another table and including fields from that result in the anonymous type, along with the entire Client object.
You can can't autogenerate every column with Linq2Sql or EF (you can however find a way to mimic this behavior with micro-orms like Dapper and massive).
More conveniently, you can just select a new anonymous type with 3 fields, firstname, lastname and a client like:
from c in dc.Clients
select new
{
FullName = c.firstname + " "+c.lastname,
Client = c
}
I would however recommend to select just those properties that you really need. This forces you to think about how to compose your query and what the query is intended to do (and hence, select). Alternatively, you can just select the client, and use some extension methods to select full names. like:
public static string GetFullName(this Client client){ return client.firstname + " " + client.lastname; }
I am creating a page which would have different field for the user to search from.
e.g. search by:
Grade: -dropdownlist1-
Student name: -dropdownlist2-
Student ID: -dropdownlist3-
Lessons: -dropdownlist4-
Year: -dropdownlist5-
How do I write the select statement for this? Each dropdownlist would need a select statement which would extract out different data from the database.
But, I want to write ONE select statement which can dynamically choose the dropdownlist options. Instead of writing many many select statement.
Lets say;
Grade: -dropdownlist1- ; default value(all)
Student name: -dropdownlist2-; default value(all)
Student ID: -dropdownlist3-; 0-100 is choosen
Lessons: -dropdownlist4-; A-C is choosen
Year: -dropdownlist5-; 2009 is choosen
It depends on the language you're using between SQL and the page. But test the dropdown for a non-generic value and then add in a where clause:
sql = "select * from people where 1 = 1";
if(dropdownlist.value != "All")
sql += "and name like '%" + dropdownlist.value + "%' ";
(watch out for SQL Injection though)
Extending to Tom's answer,
Create a view first which will contain the needed record set. Query on the view.