I've been having trouble combining multiple row values into a single column for each semester.
The table (GENERALEDPATHWAY) has these columns:
*STUDENTID
*SEMESTER
*CLASS
*CLASS_COMBINATION (all values currently null)
*YEAR
*CLASS_GRADE
*ENTRYPOINT
*DEGREE
*CLASS_DISTRIBUTION
*DEGREE
*GRADUATED_IN
I'm only currently worried about the STUDENTID, SEMESTER, CLASS, and Class_Combination. Every student has a unique ID and may have a different combination of classes each semester. Instead of having a separate row for every class every semester, I want to put the class values into the CLASS_COMBINATION column. EX: instead of having 5 rows for 5 classes taken in a single semester, I just want 1 row for that semester with all classes listed alphabetically separated by commas in the CLASS_COMBINATION column.
The difficulty I'm having is that all of the information is in a single table and needs to work in Oracle SQL Developer.
Try this query:
Select studentid, semester, class,
Listagg(class) within group (order by class) as CLASS_COMBINATION
From GENERALEDPATHWAY
Group by studentid, semester, class;
If you want to update the table. Then use it in update or merge query to update each recoed and then remove the duplicate rows.
Cheers!!
What you describe is an aggregation query, with one row per student and semester.
You do not need a separate table for this. My recommendation is either a simple query or a view.
Your data structure describes STUDENTID as the primary key. However, you specify that you have multiple rows for a STUDENTID, so something is wrong -- either your explanation or the data model. From what you describe, you want:
select STUDENTID, semester,
listagg(class ', ') within group (order by class) as classes
from GENERALEDPATHWAY
group by STUDENTID, semester;
Related
Let me illustrate this:
Student_ID
Course
StudentID1
CourseA
StudentID2
CourseB
StudentID3
CourseA CourseB
There is an existing table that has data that looks like the one above (Not exactly Student & Course, this is more for illustration purpose) and my job is to do a count of how many students for each course. The table is very huge and I do not know how many and what are the courses are out there (Easily in thousands), so wonder if there is a way I can get a list of all these courses and their counts through SQL?
The current method that my team did is SELECT DISTINCT COURSE, COUNT(STUDENT_ID) FROM TABLE GROUP BY COURSE, but this does not work because it treats "CourseA CourseB" as its own.
There are some other columns in this table that I might need to do a SUM as well.
Appreciate any advice on this, thanks!
you could use below to find number of students for each course:
select course, count(*) as no_of_students
from table
group by course;
I am working with my lab database and close to complete it. But i am stuck in a query and a few similar queries which all give back the similar results.
Here is the Query in design mode
and this is what it gives out
This query is counting the number of ID values in table PatientTestIDs whereas I want to count the number of unique PatientID values grouped by each department
I have even tried Unique Values and Unique Records properties but all the times it gives the same result.
What you want requires two queries.
Query1:
SELECT DISTINCT PatientID, DepartmentID FROM PatientTestIDs;
Query2:
SELECT Count(*) AS PatientsPerDept, DepartmentID FROM Query1 GROUP BY DepartmentID;
Nested all in one:
SELECT Count(*) AS PatientsPerDept, DepartmentID FROM (SELECT DISTINCT PatientID, DepartmentID FROM PatientTestIDs) AS Query1 GROUP BY DepartmentID;
You can include the Departments table in query 2 (or the nested version) to pull in descriptive fields but will have to include those additional fields in the GROUP BY.
Say I have a student table with the following fields - student id, student name, age, gender, marks, class.Assume that due to some error, there are multiple entries corresponding to each student. My requirement is to identify the duplicate rows in the table and the filter criterion is the student name and the class.But in the query result, in addition to identifying the duplicate records, I also need to find the original student detail which got duplicated. Is there any method to do this. I went through this answer: SQL: How to find duplicates based on two fields?. But here it only specifies how to find the duplicate rows and not a means to identify the actual row that was duplicated. Kindly throw some light on the possible solution. Thanks.
First of all: if the columns you've listed are all in the same table, it looks like your database structure could use some normalization.
In terms of your question: I'm assuming your StudentID field is a database generated, primary key and so has not been duplicated. (If this is not the case, I think you have bigger problems than just duplicates).
I'm also assuming the duplicate row has a higher value for StudentID than the original row.
I think the following should work (Note: I haven't created a table to verify this so it might not be perfect straight away. If it doesn't it should be fairly close)
select dup.StudentID as DuplicateStudentID
dup.StudentName, dup.Age, dup.Gender, dup.Marks, dup.Class,
orig.StudentID as OriginalStudentId
from StudentTable dup
inner join (
-- Find first student record for each unique combination
select Min(StudentId) as StudentID, StudentName, Age, Gender, Marks, Class
from StudentTable t
group by StudentName, Age, Gender, Marks, Class
) orig on dup.StudentName = orig.StudenName
and dup.Age = orig.Age
and dup.Gender = orig.Gender
and dup.Marks = orig.Marks
and dup.Class = orig.Class
and dup.StudentID > orig.StudentID -- Don't identify the original record as a duplicate
I need the second column of the table retrieved from a query to have a count of the number of rows, so row one would have a 1, row 2 would have a 2 and so on. I am not very proficient with sql so I am sorry if this is a simple task.
A basic example of what I am doing would be is:
SELECT [Name], [I_NEED_ROW_COUNT_HERE],[Age],[Gender]
FROM [customer]
The row count must be the second column and will act as an ID for each row. It must be the second row as the text file it is generating will be sent to the state and they require a specific format.
Thanks for any help.
With your edit, I see that you want a row ID (normally called row number rather than "count") which is best gathered from a unique ID in the database (person_id or some other unique field). If that isn't possible, you can make one for this report with ROW_NUMBER() OVER (ORDER BY EMPLOYEE_ID DESC) AS ID, in your select statement.
select Name, ROW_NUMBER() OVER (ORDER BY Name DESC) AS ID,
Age, Gender
from customer
This function adds a field to the output called ID (see my tips at the bottom to describe aliases). Since this isn't in the database, it needs a method to determine how it will increment. After the over keyword it orders by Name in descending order.
Information on Counting follows (won't be unique by row):
If each customer has multiple entries but the selected fields are the same for that user and you are counting that user's records (summed in one result record for the user) then you would write:
select Name, count(*), Age, Gender
from customer
group by name, age, gender
This will count (see MSDN) all the user's records as grouped by the name, age and gender (if they match, it's a single record).
However, if you are counting all records so that your whole report has the grand total on every line, then you want:
select Name, (select count(*) from customer) as "count", Age, Gender
from customer
TIP: If you're using something like SSMS to write a query, dragging in columns will put brackets around the columns. This is only necessary if you have spaces in column names, but a DBA will tend to avoid that like the plague. Also, if you need a column header to be something specific, you can use the as keyword like in my first example.
W3Schools has a good tutorial on count()
The COUNT(column_name) function returns
the number of values (NULL values will not be counted) of the
specified column:
SELECT COUNT(column_name) FROM table_name;
The COUNT(*) function returns the number of records in a table:
SELECT COUNT(*) FROM table_name;
The COUNT(DISTINCT column_name) function returns the number of
distinct values of the specified column:
SELECT COUNT(DISTINCT column_name) FROM table_name;
COUNT(DISTINCT) works with ORACLE and Microsoft SQL Server, but
not with Microsoft Access.
It's odd to repeat the same number in every row but it sounds like this is what you're asking for. And note that this might not work in your flavor of SQL. MS Access?
SELECT [Name], (select count(*) from [customer]), [Age], [Gender]
FROM [customer]
i have columns i.e. theory marks, pratical marks, student's Id ,course Id ,& subject Id
i need to add up the vaules present in columns theory marks & practical marks in order to get the aggregate, i dont know how to add the column values though. I am using sql server 2005
please help
assuming theory marks and practical marks are numerical data types
SELECT
student_id,
course_id,
subject_id,
SUM(theory_marks + practical_marks) AS overall_mark
FROM
table
GROUP BY
student_id, course_id, subject_id