I have a task to make a database only in MySQL. I made 11 tables and connected them via foreign keys. I tried to make a simple query in order to return name and lastname of the patient in his diagnose, but I always get only a header with the first and last name and analysis.
The patient's table has nameID, name, last name, ID serial number, date of birth and so on, but I wanted only name and last name for the test query.
The second table I joined is analysis, which has analysisID, patientID, doctorID, hospitalID, diagnosis and so on.
My query is like this:
SELECT pat.name, pat.lastname
FROM patient pat
JOIN analysis a ON pat.patientID = a.patientID
group by a.analysisID
order by pat.lastname
This query returns 0 rows. Please help, I am new at mySQL. I read a lot of tutorials, read posts here about this problem and I still didn't find a solution.
I assume that you want to eliminate any duplicate analysisID's for the same person with the use of group by. If so, you could use the following:
Select a.analysisID, pat.name, pat.lastname
from patient pat, analysis a
where pat.patientID = a.patientID
group by a.analysisID, pat.name, pat.lastname
What the above query will do is return only one record when the analysisID, name and lastname are all the same.
Related
I'm new to sql.
I have 3 datasets ,
patient (columns : id age Zip_Code, size, weight, sex)
blood_tests (columns : test_ID, test_date, blood_sugar, laboratory_ID, patient_ID)
laboratory (columns : id, name, Zip_code, departments)
how can i get the number of patients per center ?
i did this code but it doesnt give the number per
select DISTINCT patient_ID, laboratory_ID from patient,blood_tests where patient.id = blood_tests.patient_ID AND blood_tests.laboratory_ID = laboratory.id;
but i don't know how to get the total number of patients per center, because some of them did more than one exam in the same center and they have done tests in many labs?
For the second question. he aks us to get the 4 tests that a specific patient carried out in a laboratory called 'NWB'.
and i did this and noticed that he is patient with and ID = 25 but how can i get that without specifying that the id is 25.
select patient_ID, laboratory.name from patient, blood_tests,laboratory where patient_ID = blood_tests.patient_ID AND blood_tests.laboratory_ID = laboratory.id HAVING laboratory.name = "NWB";
Thank You in advance.
This query will give you the number of distinct patients that had a blood test done for each laboratory. The query GROUPs all the records with the same laboratory_ID and then counts the number of DISTINCT patients per GROUP. Distinct in this case means that each patient is only counted once per GROUP even if there are multiple records with the same patient_ID and laboratory_ID. However the patient can still be counted in other GROUPs.
SELECT laboratory_ID, COUNT(DISTINCT patient_ID)
FROM blood_tests
GROUP BY laboratory_ID;
You could join the laboratory table to show the name of the laboratory instead of the id.
SELECT laboratory.nom, COUNT(DISTINCT blood_tests.patient_ID)
FROM blood_tests
JOIN laboratory ON laboratory.id = blood_tests.laboratory_ID
GROUP BY blood_tests.laboratory_ID;
Your other question is confusing because there is no 'the' test for a patient having carried out 4 tests. There would be 4 tests - which one of them is 'the' test.
Here is a query that will list the ids of all patients that have had 4 test carried out at the laboratory with the id 42.
SELECT patient_ID
FROM blood_tests
WHERE laboratory_ID = 42
GROUP BY patient_ID
HAVING COUNT(patient_ID) = 4;
EDIT based on comment from OP:
I hope this is useful for anyone trying to learn how to query a database.
When you query a database your asking it for information based on what is found in the database not based on what you already know to be true. You first need to figure out what it is that you are asking.
If you say you know that there is some (some means at least one) specific patient that did exactly 4 tests at laboratory NWB, you could ask the database to list all patients that carried out exactly 4 tests at laboratory NWB.
If you know the specific patient and want to get the tests then you would ask the database for all the tests carried out at at laboratory NWB for this specific patient. In this case the fact that you know there are 4 of them is not a criteria for selection, so it wouldn't appear in your query.
If you know there is some patient that did exactly 4 tests and you want to get their tests. What are you asking the database? You could ask: Find me all tests for any patient that has done exactly 4 tests at laboratory NWB. But if there are other patients that also had exactly 4 tests at that laboratory you would get their tests as well.
Above you saw how to group records together by a criteria and how to count the members of each group.
The HAVING clause allows you to limit results based on criteria that applies to a group.
The WHERE clause allows you to limit results based on criteria that applies to a record.
You should be able to construct a query for any of those scenarios using what was shown above.
You need to use COUNT(DISTINCT ~ ) and GROUP BY. We don't need to use the table patients because we have patient_ID in blood_tests.
SELECT
COUNT( DISTINCT bt.patient_ID) number_patients ,
bt.laboratory_ID
FROM
blood_tests bt
JOIN
laboratory l
ON bt.laboratory_ID = l.id
GROUP BY
laboratory_ID;
For the second request:
SELECT
GROUP_CONCAT(
bt.test_ID
SEPARATOR CHAR(10)
) test_IDs,
bt.patient_ID patientID,
bt.laboratory_ID. labo_ID,
l.name lab_name,
l.Zip_code. lab_zip,
l.departments. lab_dept
FROM
blood_tests bt
JOIN
laboratory l
ON
bt.laboratory_ID = l.id
WHERE
l.name = 'NWB'
GROUP BY
bt.patient_ID ,
bt.laboratory_ID,
l.name lab_name,
l.Zip_code,
l.departments
HAVING
COUNT(bt.test_ID) = 4;
Assuming you're using Mysql with PhpMyAdmin (from now i'll call it PMA)
You get the COUNT of patients for each laboratory using GROUP BY keyword.
You can read the (unofficial) documentation here.
Using GROUP BY you can get the count of tests for each laboratory with
SELECT laboratory_ID, COUNT(*) As num_tests FROM blood_tests WHERE 1 GROUP BY laboratory_ID;
So the query returns 2 columns one for the laboratory ID and one for the number of tests for that one.
You can see the zip code of laboratory using JOINS statements, in this case you should use INNER JOIN click here for (unofficial) documentation
I've made a table with the columns for a customer name and each activity they participate in. How can I can I count the activities for each name and display it?
I've done;
SELECT Activity_Name, COUNT(*) AS 'Number_of_activities'
FROM tablename
GROUP BY Activity_Name;
which gives me each a table of each activity and how many participants in each activity but not each customer and their number of activities
Apologies for anything I've done wrong, only a couple months into coding and first time posting on stack...
Considering I don't know how your schema looks exactly, this query should be a nice representation of the idea how to do it:
SELECT customer_name, COUNT(*) AS 'Number_of_activities_per_customer'
FROM tablename
GROUP BY customer_name;
I've got a table with 11 columns and I want to create a query that removes the rows with duplicate names in the Full Name's column but keeps the row with the lowest value in the Result's column. Currently I have this.
SELECT
MIN(sql363686.Results2014.Result),
sql363686.Results2014.Temp,
sql363686.Results2014.Full Name,
sql363686.Results2014.Province,
sql363686.Results2014.BirthDate,
sql363686.Results2014.Position,
sql363686.Results2014.Location,
sql363686.Results2014.Date
FROM
sql363686.Results2014
WHERE
sql363686.Results2014.Event = '50m Freestyle'
AND sql363686.Results2014.Gender = 'M'
AND sql363686.Results2014.Agegroup = 'Junior'
GROUP BY
sql363686.Results2014.Full Name
ORDER BY
sql363686.Results2014.Result ASC ;
At first glance it seems to work fine and I get all the correct values, but I seem to be getting a different (wrong) value in the Position column then what I have in my database table. All other values seem to be right. Any ideas on what I'm doing wrong?
I'm currently using dbVisualizer connected to a mysql database. Also, my knowledge and experience with sql is the bare mimimum
Use group by and a join:
select r.*
from sql363686.Results2014 r
(select fullname, min(result) as minresult
from sql363686.Results2014 r
group by fullname
) rr
on rr.fullname = r.fullname and rr.minresult = r.minresult;
You have fallen into the trap of the nonstandard MySQL extension to GROUP BY.
(I'm not going to work with all those fully qualified column names; it's unnecessary and verbose.)
I think you're looking for each swimmer's best time in a particular event, and you're trying to pull that from a so-called denormalized table. It looks like your table has these columns.
Result
Temp
FullName
Province
BirthDate
Position
Location
Date
Event
Gender
Agegroup
So, the first step is to locate the best time in each event for each swimmer. To do this we need to make a couple of assumptions.
A person is uniquely identified by FullName, BirthDate, and Gender.
An event is uniquely identified by Event, Gender, Agegroup.
This subquery will get the best time for each swimmer in each event.
SELECT MIN(Result) BestResult,
FullName,BirthDate, Gender,
Event, Agegroup
FROM Results2014
GROUP BY FullName,BirthDate, Gender, Event, Agegroup
This gets you a virtual table with each person's fastest result in each event (using the definitions of person and event mentioned earlier).
Now the challenge is to go find out the circumstances of each person's best time. Those circumstances include Temp, Province, Position, Location, Date. We'll do that with a JOIN between the original table and our virtual table, like this
SELECT resu.Event,
resu.Gender,
resu.Agegroup,
resu.Result,
resu.Temp.
resu.FullName,
resu.Province,
resu.BirthDate,
resu.Position,
resu.Location,
resu.Date
FROM Results2014 resu
JOIN (
SELECT MIN(Result) BestResult,
FullName,BirthDate, Gender,
Event, Agegroup
FROM Results2014
GROUP BY FullName,BirthDate, Gender, Event, Agegroup
) best
ON resu.Result = best.BestResult
AND resu.FullName = best.FullName
AND resu.BirthDate = best.BirthDate
AND resu.Gender = best.Gender
AND resu.Event = best.Event
AND resu.Agegroup = best.Agegroup
ORDER BY resu.Agegroup, resu.Gender, resu.Event, resu.FullName, resu.BirthDate
Do you see how this works? You need an aggregate query that pulls the best times. Then you need to use the column values in that aggregate query in the ON clause to go get the details of the best times from the detail table.
If you want to report on just one event you can include an appropriate WHERE clause right before ORDER BY as follows.
WHERE resu.Event = '50m Freestyle'
AND resu.Gender = 'M'
AND resu.Agegroup = 'Junior'
I am trying to select a small number of records in a somewhat large database and run some queries on them.
I am incredibly new to programming so I am pretty well lost.
What I need to do is select all records where the Registraton# column equals a certain number, and then run the query on just those results.
I can put up what the db looks like and a more detailed explanation if needed, although I think it may be something simple that I am just missing.
Filtering records in a database is done with the WHERE clause.
Example, if you wanted to get all records from a Persons table, where the FirstName = 'David"
SELECT
FirstName,
LastName,
MiddleInitial,
BirthDate,
NumberOfChildren
FROM
Persons
WHERE
FirstName = 'David'
Your question indicates you've figured this much out, but are just missinbg the next piece.
If you need to query within the results of the above result set to only include people with more than two children, you'd just add to your WHERE clause using the AND keyword.
SELECT
FirstName,
LastName,
MiddleInitial,
BirthDate,
NumberOfChildren
FROM
Persons
WHERE
FirstName = 'David'
AND
NumberOfChildren > 3
Now, there ARE some situations where you really need to use a subquery. For example:
Assuming that each person has a PersonId and each person has a FatherId that corresponds to another person's PersonId...
PersonId FirstName LastName FatherId...
1 David Stratton 0
2 Matthew Stratton 1
Select FirstName,
LastName
FROM
Person
WHERE
FatherId IN (Select PersonId
From Person
WHERE FirstName = 'David')
Would return all of the children with a Father named David. (Using the sample data, Matthew would be returned.)
http://www.w3schools.com/sql/sql_where.asp
Would this be any use to you?
SELECT * from table_name WHERE Regestration# = number
I do not know what you have done up to now, but I imagine that you have a SQL query somewhere like
SELECT col1, col2, col3
FROM table
Append a where clause
SELECT col1, col2, col3
FROM table
WHERE "Registraton#" = number
See SO question SQL standard to escape column names?.
Try this:
SELECT *
FROM tableName
WHERE RegistrationNo = 'valueHere'
I am not certain about my solution. I would propose You to use view. You create view based on needed records. Then make needed queries and then you can delete the view.
View description: A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database.
Example:
CREATE VIEW view_name AS
SELECT column_name(s)
FROM table_name
WHERE condition
For more information: http://www.w3schools.com/sql/sql_view.asp
I have a small problem regarding a count after grouping some elements from a mysql table,
I have an orders table .. in which each order has several rows grouped by a code (named as codcomanda) ... I have to do a query which counts the number of orders per customer and lists only the name and number of orders.
This is what i came up (this might be dumb ... i'm not a pro programmer)
SELECT a.nume, a.tel, (
SELECT COUNT(*) AS `count`
FROM (
SELECT id AS `lwtemp`
FROM lw_comenzi_confirmate AS yt
WHERE status=1 AND yt.tel LIKE **a.tel**
GROUP BY yt.codcomanda
) AS b
) AS numar_comenzi
FROM lw_comenzi_confirmate AS a
WHERE status=1
GROUP BY tel;
nume = NAME
tel = PHONE (which is the distinct identifier for clients since there's no login system)
The problem with the above query is that I don't know how to match the a.tel with the one on which the first select is on. If I replace it with a number that is in the db it works....
Can anyone help me one how to refer to that var?
or maybe another solution on how to get this done?
If any more info is needed I`ll provide asap.
Please, correct me if I'm wrong in my understanding of your schema:
lw_comenzi_confirmate contains nume and tel of the customer;
lw_comenzi_confirmate contains order details (same table);
one order can have several entries in the lw_comenzi_confirmate table, order is distinguished by codcomanda field.
First, I highly recommend reading about Normalisation and fixing your database design.
The following should do the job for you:
SELECT nume, tel, count(DISTINCT codcomanda) AS cnt
FROM lw_comenzi_confirmate
WHERE status = 1
GROUP BY nume, tel
ORDER BY nume, tel;
You can test this query on SQL Fiddle.