I am Omar, a new learner of SQL.
I have a large excel sheet that I want to analyze by SQL.
It has the following columns (Manufacturers, Products, sales)
the problem is, in the first column 'Manufacturers,' the manufacturer name has only been entered once per one manufacturer. while for the rest of the below rows, the cells are empty until the next manufacturer.
Please refer to the attached image for more understanding.
How can I remove these null values in my query results while keeping the values of the product column value?
thank you
The main problem you have is that SQL tables represent unordered sets. So, if you have only your specified columns, you cannot reconstruct the Excel format.
To solve this, you want to load the data into a table that has an identity or auto-incremented column, in order to preserve the insertion order. The exact details depend on the database. Let me call this column id.
Then you can "spread" the value where it is missing. One method is:
select t.*,
max(manufacturer) over (partition by manufacturer_grp) as imputed_manufacturer
from (select t.*,
count(manufacturer) over (order by id) as manufacturer_grp
from t
) t
Related
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
How do I insert a row between here?
Data is not intended to be stored SQL tables in any particular order, so it's not appropriate to insert a row at a particular position. You use an SQL SELECT query to extract the data you want and ORDER BY to specify how it is sorted. If you really want to have this row in a particular position, add an ID column as the primary key and number the ID column values in the sequence that you want. Whatever you are using to view your rows will order them by the ID column by default. However, you're going to experience this same problem every time you want to add a new row as SQL tables are not intended to be used in this way.
I can’t find how to rename the row counting column in a table in an SQL Server RDMS. When you create a table and you have user created columns, A and B for example, to the farthest right of those columns, you have the Row Number column.
It does not have a title. It just sequentially counts all the rows in your table. It's default. Is it possible to manipulate this column denoting the row numbers? Meaning, can I rename it, put its contents in descending order, etc. If so, how?
And if not, what are the alternatives to have a sequentially counting column counting all the rows in my table?
No. You can create your own column with sequential values using an identity column. This is usually a primary key.
Alternatively, when you query the table, you can assign a sequential number (with no gaps) using row_number(). In general, you want a column that specifies the ordering:
select t.*, row_number() over (order by <ordering column>) as my_sequential_column
from t;
I need to insert a row at the top of my table. Is there a way to do that?
I am aware of "Order By" and that is not going to work. I need to change the actual table (Please do not suggest Order By. Most of the threads I found here only suggests that).
The column contains dates. The table is already ordered by desc when the data is input. Everyday, I need to add a row that has the current date and populate the rest of the data based on that. That row has to be on the top.
I have an ID Column. It is not a primary key. It goes 1, 2, 3...
The new date that is added should ideally be inserted on row 1 with it's ID being 1 (That's not absolutely vital though). I am okay with ID being all over the place but the dates have to be all descending.
Edit: I have added screenshots of the table before insert and after. The table has some 300 rows of data. As you can see, after the insert, the current date goes to the bottom. I want to change that.
Please help. Thanks
If you read the following response to a question asked previously, it will detail why you must use order by due to the order of the rows being returned never being guaranteed:
Default row order in SELECT query
Therefore just insert the data into the table, what SQL does with it in the background is irrelevant to you, what is relevant is the order in which you request them to be retrieved. Therefore Order By is the way to get the data out in the order that you want.
I'm struggling to understand what you mean by:
The table is already ordered by desc when the data is input.
It should be a two stage process:
1) Insert Data
INSERT INTO [TABLENAME] VALUES ([ID], [risk_date_day], [Risk1], [Risk2], [Risk3], [Risk4], [Risk5], [Grand Total], [1Per], [2Per], [3Per], [4Per], [5Per]);
--Naturally replace the values between square brackets with the correct values for data entry.
2) Retrieve Data
SELECT [ID], [risk_date_day], [Risk1], [Risk2], [Risk3], [Risk4], [Risk5], [Grand Total], [1Per], [2Per], [3Per], [4Per], [5Per]
FROM [TABLENAME]
ORDER BY [risk_date_day] DESC;
This will return the data with the latest date at the top.
However if you are in fact saying that the date you could enter on any particular day may not necessarily be the latest date, then this will not work. In which case I would suggest adding a field called DateOfEntry and use that field to do the Order By.
I am trying to insert values from a table into another existing table and have just the values I am inserting be sorted in descending order based on a specific column while leaving the existing records at the top of the table. How do I do that? I have tried to use an Order By statement but whether I use the column name of the table I'm pulling from or the destination table's column name I get an error. Also this is being run in VBA using DoCmd.RunSQL.
Here is my existing query:
INSERT INTO AllMetersAvgRSSI
(longitude,latitude,AvgRSSI)
Select
Prem.longitude, Prem.latitude,
DataByColl.[Avg RSSI]
From [Prem]
Left
Join DataByColl ON (Prem.meter_miu_id
= DataByColl.[MIU ID])
Order BY [AvgRSSI] desc
Final Result
I continued to fiddle with this and discovered than you can use an order by just like I have shown above to do exactly as I was trying to do. The problem I was apparently having was caused by the names of the column I wanted sorted being changed only from Avg RSSI to AvgRSSI. When I changed the destination table to have the same field name as the source table it orders the incoming information while leaving the existing information alone. I also did a test where I changed the name of the destination table to AverageRSSI and it worked the same way. So in the end it was the names of the fields being differed only by a space that was causing the problem. The final Query is:
INSERT INTO AllMetersAvgRSSI
(longitude,latitude,[Avg RSSI])
Select
Prem.longitude, Prem.latitude,
DataByColl.[Avg RSSI]
From [Prem]
Left
Join DataByColl ON (Prem.meter_miu_id
= DataByColl.[MIU ID])
Order BY [Avg RSSI] desc
Ordering in an INSERT makes no sense from a database standpoint. How the database puts the rows into a table depends on the underlying physical structure of the table, not the order in which they are inserted.
Maybe your application relies on an auto incrementing column being in a certain order which would then be dependent on the order of insertion, but if that's the case then I would say that you've made a mistake in your database design as there shouldn't be business logic designed around an auto incrementing column.
Remove the ORDER BY from your INSERT statement and if you need to retrieve rows in a particular order later then use an ORDER BY there.
Create a temp table, add the first result set in the desired order. Insert your new values into the table, query the table to return your new results with an order by into your temp table, select your temp table the results will be in the order you added them unless you do another order by.
Don't forget to drop your temp table after displaying the results.