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How to insert lists to a table without repeating them if they already exist (Using Spring and Hibernate)

first of all, I'd like to point out I'm new to Spring and Hibernate.
I've been trying to connect Hibernate with MySQL (using Spring Data), which I've done successfuly, however, when I try to do an insert I can't get it to do what I want.
What I'm trying to accomplish is to have a User class, with an ArrayList that contains their preferred coding languages.
For example:
User 1: C, Java, C++
User 2: Python, Java, C++
However, I've noticed that Hibernate will create a new row in the "Languages" table even if it's already there. I also want to keep the "id" as a primary key and as a numeric value.
The following is how it currently inserts the languages to the table:
+----+--------+
| id | name |
+----+--------+
| 2 | C |
| 3 | Java |
| 4 | C++ |
| 6 | Python |
| 7 | Java |
| 8 | C++ |
+----+--------+
This is how I want them:
+----+--------+
| id | name |
+----+--------+
| 2 | C |
| 3 | Java |
| 4 | C++ |
| 6 | Python |
+----+--------+
I've tried different methods, but it's always repeating the values...
This is my user class:
#Entity
public class User {
#Id
#GeneratedValue
private int id;
private String username;
#OneToMany(cascade = CascadeType.ALL)
private List<Language> languages;
...
}
And this is my Language class:
#Entity
public class Language {
#Id
#GeneratedValue
private int id;
private String name;
...
}
This is how I'm adding the languages to each user (it's just a test, not final code):
ArrayList<Language> languages = new ArrayList<>();
languages.add(new Language("C"));
languages.add(new Language("Java"));
languages.add(new Language("C++"));
Image image = null;
User admin = new User("iscle", "albertiscle9#gmail.com", "Test_Password", languages, image);
userRepository.save(admin);
ArrayList<Language> languages2 = new ArrayList<>();
languages2.add(new Language("Python"));
languages2.add(new Language("Java"));
languages2.add(new Language("C++"));
Image image2 = null;
User admin2 = new User("iscle", "albertiscle9#gmail.com", "Test_Password", languages2, image2);
userRepository.save(admin2);

make attribute name (Languages) "UNIQUE"; then you ensure that there will be no duplicate

Elasticsearch - how to group by and count matches in an index

I have an instance of Elasticsearch running with thousands of documents. My index has 2 fields like this:
|____Type_____|__ Date_added __ |
| walking | 2018-11-27T00:00:00.000 |
| walking | 2018-11-26T00:00:00.000 |
| running | 2018-11-24T00:00:00.000 |
| running | 2018-11-25T00:00:00.000 |
| walking | 2018-11-27T04:00:00.000 |
I want to group by and count how many matches were found for the "type" field, in a certain range.
In SQL I would do something like this:
select type,
count(type)
from index
where date_added between '2018-11-20' and '2018-11-30'
group by type
I want to get something like this:
| type | count |
| running | 2 |
| walking | 3 |
I'm using the High Level Rest Client api in my project, so far my query looks like this, it's only filtering by the start and end time:
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders
.boolQuery()
.must(QueryBuilders
.rangeQuery("date_added")
.from(start.getTime())
.to(end.getTime()))
)
);
How can I do a "group by" in the "type" field? Is it possible to do this in ElasticSearch?

That's a good start! Now you need to add a terms aggregation to your query:
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(QueryBuilders.boolQuery()
.must(QueryBuilders
.rangeQuery("date_added")
.from(start.getTime())
.to(end.getTime()))
)
);
// add these two lines
TermsAggregationBuilder groupBy = AggregationBuilders.terms("byType").field("type.keyword");
sourceBuilder.aggregation(groupBy);

After using Val's reply to aggregate the fields, I wanted to print the aggregations of my query together with the value of them. Here's what I did:
Terms terms = searchResponse.getAggregations().get("byType");
Collection<Terms.Bucket> buckets = (Collection<Bucket>) terms.getBuckets();
for (Bucket bucket : buckets) {
System.out.println("Type: " + bucket.getKeyAsString() + " = Count("+bucket.getDocCount()+")");
}
This is the output after running the query in an index with 2700 documents with a field called "type" and 2 different types:
Type: walking = Count(900)
Type: running = Count(1800)

MySQL query to fetch list of data using logical operations

The following are the list of different kinds of books that customers read in a library. The values are stored with the power of 2 in a column called bookType.
I need to fetch list of books with the combinations of persons who read
only Novel Or only Fairytale Or only BedTime Or both Novel + Fairytale
from the database with logical operational query.
Fetch list for the following combinations :
person who reads only novel(Stored in DB as 1)
person who reads both novel and fairy tale(Stored in DB as 1+2 = 3)
person who reads all the three i.e {novel + fairy tale + bed time} (stored in DB as 1+2+4 = 7)
The count of these are stored in the database in a column called BookType(marked with red in fig.)
How can I fetch the above list using MySQL query
From the example, I need to fetch users like novel readers (1,3,5,7).

The heart of this question is conversion of decimal to binary and mysql has a function to do just - CONV(num , from_base , to_base );
In this case from_base would be 10 and to_base would be 2.
I would wrap this in a UDF
So given
MariaDB [sandbox]> select id,username
-> from users
-> where id < 8;
+----+----------+
| id | username |
+----+----------+
| 1 | John |
| 2 | Jane |
| 3 | Ali |
| 6 | Bruce |
| 7 | Martha |
+----+----------+
5 rows in set (0.00 sec)
MariaDB [sandbox]> select * from t;
+------+------------+
| id | type |
+------+------------+
| 1 | novel |
| 2 | fairy Tale |
| 3 | bedtime |
+------+------------+
3 rows in set (0.00 sec)
This UDF
drop function if exists book_type;
delimiter //
CREATE DEFINER=`root`#`localhost` FUNCTION `book_type`(
`indec` int
)
RETURNS varchar(255) CHARSET latin1
LANGUAGE SQL
NOT DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT ''
begin
declare tempstring varchar(100);
declare outstring varchar(100);
declare book_types varchar(100);
declare bin_position int;
declare str_length int;
declare checkit int;
set tempstring = reverse(lpad(conv(indec,10,2),4,0));
set str_length = length(tempstring);
set checkit = 0;
set bin_position = 0;
set book_types = '';
looper: while bin_position < str_length do
set bin_position = bin_position + 1;
set outstring = substr(tempstring,bin_position,1);
if outstring = 1 then
set book_types = concat(book_types,(select trim(type) from t where id = bin_position),',');
end if;
end while;
set outstring = book_types;
return outstring;
end //
delimiter ;
Results in
+----+----------+---------------------------+
| id | username | book_type(id) |
+----+----------+---------------------------+
| 1 | John | novel, |
| 2 | Jane | fairy Tale, |
| 3 | Ali | novel,fairy Tale, |
| 6 | Bruce | fairy Tale,bedtime, |
| 7 | Martha | novel,fairy Tale,bedtime, |
+----+----------+---------------------------+
5 rows in set (0.00 sec)
Note the loop in the UDF to walk through the binary string and that the position of the 1's relate to the ids in the look up table;
I leave it to you to code for errors and tidy up.

Load string array from database

What's easiest way to load address field content into a string array from a Postgres database:
id | name | address
-----------------------------------------------------------------
1 | John | {"line1","line2","line3"}
2 | Steve | {"addr1","addr2","addr3"}
String[0] = "line1"
String[1] = "line2"
String[2] = "line3"
I'm not sure if this is a serialized string array but somehow i'm failing on this simple task.

Removing null elements and keeping non-null elements together on a list in jasper reports

I am using JRBeanCollectionDataSource as datasource for a subreport. Each record in the list contains elements with either null or non-null value . This is my POJO:
public class PayslipDtl {
private String earningSalaryHeadName;
private double earningSalaryHeadAmount;
private String deductionSalaryHeadName;
private double deductionSalaryHeadAmount;
String type;
public PayslipDtl(String salaryHeadName,
double salaryHeadAmount, String type) {
if(type.equalsIgnoreCase("Earning")) {
earningSalaryHeadName = salaryHeadName;
earningSalaryHeadAmount = salaryHeadAmount;
} else {
deductionSalaryHeadName = salaryHeadAmount;
deductionSalaryHeadAmount = salaryHeadAmount;
}
}
//getters and setters
}
Based on the "type", the list is populated as such: {"Basic", 4755, null, 0.0}, {"HRA", 300, null, 0.0}, {null, 0.0, "Employee PF", 925}, {"Medical Allowance", 900, null, 0.0} and so on...
After setting isBlankWhenNull to true and using "Print when" expression, the record is displayed as such:
|Earning |Amount|Deduction |Amount|
--------------------|------|---------------------|------|
| Basic | 4755 | | |
| HRA | 300 | | |
| | | Employee PF | 925 |
| Medical Allowance | 900 | | |
| Fuel Reimbursement| 350 | | |
| | | Loan | 1000 |
---------------------------------------------------------
I want it to be displayed as such:
|Earning |Amount|Deduction |Amount|
--------------------|------|---------------------|------|
| Basic | 4755 | Employee PF | 925 |
| HRA | 300 | Loan | 1000 |
| Medical Allowance | 900 | | |
| Fuel Reimbursement| 350 | | |
---------------------------------------------------------
Setting isRemoveLineWhenBlank to true doesn't work since it is not the entire row which is blank but only a subset of elements of a row that is null.
Is it possible in Jasper?
I am using iReport Designer 5.0.1 with compatibility set to JasperReports3.5.1.

Use a List component for the deduction/amount, here you have a video tutorial on how to do this.
Then deduction and amount fields on the list component need the following options Blank when null and Remove line when blank.
If this still gives you blank lines, try putting both fields on a frame inside the list and mark those options for the frame too.

Only one good solution is, you have to create separate table as:
table employeeED:
srno int,
Earning varchar(50),
EarnAmount Double,
Deduction varchar(50)
DedAmount Double
then you have to insert all earnings in earning side and update all deductions in deductions side.
int i=1;
rs.first();
while(rs.next())
{
if(rs.getString("type").equals("Earning"))
Insert into employeeEd (srno, Earning,EarnAmount) values (i, rs('earning'), rs('eamt'))
}
int j=1;
rs.first();
while(rs.next())
{
if(rs.getString("type").equals("deduction"))
update employeeEd set Deductions='"+rs('earning')+"', DedAmount=" + rs('eamt') + " where srno="+j)
j++;
}
then use employeeED table as datasource.
100% working.