SQL to identify duplicate columns from table having hundreds of column - sql

I've 250+ columns in customer table. As per my process, there should be only one row per customer however I've found few customers who are having more than one entry in the table
After running distinct on entire table for that customer it still returns two rows for me. I suspect one of column may be suffixed with space / junk from source tables resulting two rows of same information.
select distinct * from ( select * from customer_table where custoemr = '123' ) a;
Above query returns two rows. If you see with naked eye to results there is not difference in any of column.
I can identify which column is causing duplicates if I run query every time for each column with distinct but thinking that would be very manual task for 250+ columns.
This sounds like very dumb question but kind of stuck here. Please suggest if you have any better way to identify this, thank you.

Solving this one-time issue with sql is too much effort. Simply copy-paste to excel, transpose data into columns and use some simple function like "if a==b then 1 else 0".

Related

Removing rows with duplicated column values based on another column's value

Hey guys, maybe this is a basic SQL qn. Say I have this very simple table, I need to run a simple sql statement to return a result like this:
Basically, the its to dedup Name based on it's row's Value column, whichever is larger should stay.
Thanks!
Framing the problem correctly would help you figure it out.
"Deduplication" suggests altering the table - starting with a state with duplicates, ending with a state without them. Usually done in three steps (getting the rows without duplicates into temp table, removing original table, renaming temp table).
"Removing rows with duplicated column values" also suggests alteration of data and derails train of thought.
What you do want is to get the entire table, and in cases where the columns you care about have multiple values attached get the highest one. One could say... group by columns you care about? And attach them to the highest value, a maximum value?
select id,name,max(value) from table group by id,name

Bigquery - remove duplicates of certain columns, but not all

I have two tables I am left joining together. The first tables has transnational level detail, causing the key I join to the second table to duplicate. When I left join the second table, the measure "company_spend" is highly inflated.
I need a way to keep only a single value of the duplicated data, and my thought was to run a distinct function on only those columns, but I am not seeing that Bigquery supports distinct functions on only a few columns, but not all.
SELECT UPPER(cwnextt.Current_Contract_Number) AS Current_Contract_Number,
UPPER(cwnextt.Replacement_Contract_Number) AS Replacement_Contract_Number,
UPPER(cwnextt.Current_Contract_Name) AS Current_Contract_Name,
UPPER(cwnextt.Supplier_Top_Parent_Entity_Code) AS Supplier_Top_Parent_Entity_Code,
UPPER(cwnextt.Supplier_Top_Parent_Name) AS Supplier_Top_Parent_Name,
UPPER(cwnextt.company_Entity_Code) AS company_Entity_Code,
UPPER(cwnextt.Facility_Name) AS Facility_Name,
smart.company_Spend AS companySpend
FROM `test_etl_field.contracts_with_member_entity_codes_test_view_2` cwnextt
--this table is what is causing the below table to duplicate,
--but I need all of this data AS well in its current format.
LEFT JOIN `test.trans_analysis` tsa
ON TRIM(UPPER(cwnextt.company_entity_code)) = TRIM(UPPER(tsa.company_entity_code))
AND TRIM(UPPER(cwnextt.Supplier_Top_Parent_Entity_Code)) = TRIM(UPPER(tsa.manufacturer_top_parent_entity_code))
AND TRIM(UPPER(cwnextt.Current_Contract_Name)) = TRIM(UPPER(tsa.contract_category))
AND cwnextt.spend_period_yyyyqmm = tsa.spend_period_yyyyqmm
--this table contains "company_spend" which is now duplicated
LEFT JOIN `test_etl_field.ecr_smart_data` smart
ON smart.company_entity_code = cwnextt.company_entity_code
AND (smart.contract_number = cwnextt.current_contract_number
OR smart.contract_number = cwnextt.replacement_contract_number)
AND smart.month_key = cwnextt.spend_period_yyyyqmm
If something can be created that will keep company_spend from duplicating on the second left join, that is what I am after.
Not sure to understand all the details of your problem but here's a fact from BigQuery doc :
SELECT DISTINCT
A SELECT DISTINCT statement discards duplicate rows
and returns only the remaining rows.
You can't apply DISTINCT on specific columns because it doesn't make sense. Let's say you have 4 columns and call DISTINCT on 3 columns, what is SQL supposed to do with the last one ?
You must tell SQL which value to keep for the remaining column and GROUP BY is the right solution here.
So if you want to:
Remove a column that has been duplicated : Just adjust your SELECT to get only the columns you want
Remove lines that have the same value in specific columns : I would suggest a GROUP BY on the targeted column and taking the aggregation you want (first, avg, sum or whatever) for the remaining ones.
Remove the value from a row if another row has the same : You may not want to do that. A row has to keep its value and you won't get it back. Besides, same problem, which row do you want to keep ?
Hope this helps ! Feel free to give clarification on your problem if you want more specific answers.
While I couldn't resolve this issue in SQL, I used Tableau via a FIXED LOD to aggregate the data passed duplicates so the end user could visualize the output with accuracy. Not ideal, but the SQL route wasn't make sense.

select only specific number of columns from Table - Hive

How to select only specific number of columns from a table in hive. For Example, If I have Table with 50 Columns, then how Can I just select first 25 columns ? Is there any easy way to do it rather than hard coading the column names.
I guess that you're asking about using the order in which you defined your columns in your CREATE TABLE statement. No, that's not possible in Hive for the moment.
You could do the trick by adding a new column COLUMN_NUMBER and use that in your WHERE statements, but in that case I would really think twice of the trade off between spending some more time typing your queries and messing your whole table design by adding unnecessary columns. Apart from the fact that if you need to change your table schema in the future (for instance, by adding a new column), adapting your previous code with different column numbers would be painful.

How to repeat records in access table number of times

I need your assistance to figure out how to achieve the following in MS access database.
I have a table with a lot of columns but one of them has a numeric value that will be used as how many times will the record will be repeated.
I need to make another table with repeated records based on Count column.
Build a numbers (aka tally) table (you can google it). I'll call it tblNumbers. Then all you need to do is create a query SELECT <yourTable>.* FROM <yourTable>, tblNumbers WHERE tblNumbers.Number <= <yourTable>.<numberField>

Joining multiple Tables in Oracle gives out duplicated records

I am a newbie to sql. I have three tables mr1,mr2,mr3. Caseid is the primary keys in all these tables. I need to join all these table columns and display result.
Problem is that i dont know which join to use.
when i joined all these just like below query:
select mr1.col1,mr1.col2,mr2.col1,mr2.col2,mr3.col1,mr3.col2
from mr1,mr2,mr3
where mr1.caseid = mr2.caseid
and mr2.caseid = mr3.caseid;
it displays 4 records, eventhough the maximum number of records is two, which is in table mr2.
records are duplicated, can anyone help me in this regard?
Distinct will do it but it's not the correct approch.
You need to add another join (mr1.caseid = mr3.caseid) because mr2 and mr3 rows must be related to the same row in mr1, otherwise you end up with 2 pairs, onde for each tabled joined to your primary table (mr2).
First answer in SO, so forgive me if it wasn't that clear.
Your problem is that your tables are in a one-to many relationship. When you join them, it is expected that the number of rows will go up unless you take steps to limit the records returned. How to fix depends on the meaning of the data.
If all the fields are exactly the same, then adding DISTINCT will fix the problem. However, it may be faster, depending on the size of the tables and the number of records you are returning, to use a derived table to limit the records in the join to only one from the table with multiple records.
If at least one of the fields is different however, then you need to know the business rule that will allow you to pick the correct record. It might be accomplished by adding a where clause or by using an aggregate function and group by or even both. This really depends on the meaning of the result set which is why you need to ask further question in your own organization as they are the only ones who will know which of the multiple records is the correct one to pick from the perspectives of the people who will be using the results of the query. Further, the business might actually want to see all of the records and you have no problem at all.