So I am working in Ruby, and say I have 6 rows in a table of two columns that are exactly identical. In my case, my table "campaign_items" has two columns "campaign_name" and "item." I would like to delete only one row out of the 6 duplicates using a single query. I started with this:
db.exec("DELETE FROM products WHERE campaign_name = '#{camp_name}' AND product_type = 'fleecejacket' AND size = '#{size_array[index]}'")
Which of course deleted all items of that condition. So I found in another question an answer along these lines:
db.exec("DELETE FROM products a WHERE a.ctid <> (SELECT min(b.ctid) FROM products b WHERE a.key = b.key)")
However, this would delete all duplicates except for one. I have not found a way that only deletes a SINGLE row that has duplicates. Is there a delete top query that I am looking for? Thanks in advance.
Edit: I also have a column "id" which is a primary key.
So I definitely overthought this, but all that is needed is this:
x = db.exec("SELECT * FROM campaign_items WHERE campaign_name = '#{camp_name}' AND item = 'fleecejacket'")
id = x[0]['id']
db.exec("DELETE FROM campaign_items WHERE campaign_name = '#{camp_name}' AND item = 'fleecejacket' AND id = '#{id}'")
Get the unique id from the first duplicate (since it doesn't matter which one is deleted) and delete the row with that id.
Related
I have an Excel template file with a dynamic number of columns that represent work week dates. Some users have decided to add their own subtotal columns to the right of those columns. I need a way to identify the first blank column, and then truncate that column and all columns following it.
I had previously been using the following script to remove all columns that begin with the word "Column":
// Create a list of columns that start with "Column" and remove them.
Removed_ColumnNum_Columns = Table.RemoveColumns(PreviousStepName, List.Select(Table.ColumnNames(PreviousStepName), each Text.StartsWith(_, "Column") )),
Based on being able to find the first ColumnXX column, I want to remove it and all columns after it
You can use List.PositionOf to get your ColumnIndex instead of parsing text.
I'd put it together like this:
// [...]
ColumnList = Table.ColumnNames(#"Promoted Headers"),
ColumnXX = List.Select(ColumnList, each Text.StartsWith(_, "Column")){0},
ColumnIndex = List.PositionOf(ColumnList, ColumnXX),
ColumnsToKeep = List.FirstN(ColumnList, ColumnIndex),
FinalTable = Table.SelectColumns(#"Promoted Headers", ColumnsToKeep)
Remove Columns after ColumnXX
Find the first column that begins with the name "Column" and delete that column and all columns following it. This parses the XX as the column index so you need to make sure you haven't deleted columns prior to this step. i.e. "Column35" needs to be the 35th column at this step in the code.
// Find the first ColumnXX column and remove it and all columns to the right.
ColumnXX = List.Select(Table.ColumnNames(#"Promoted Headers"), each Text.StartsWith(_, "Column")){0},
ColumnIndex = Number.FromText(Text.Middle(ColumnXX, 6,4)),
ColumnListToRemove = List.Range(Table.ColumnNames(#"Promoted Headers"),ColumnIndex-1),
RemovedTrailingColumns = Table.RemoveColumns(#"Promoted Headers", ColumnListToRemove),
To make this more robust I would prefer to have a way to identify the column index of columnXX without parsing the digits from it.
I hope one can help me, I am new in linq,
I have 2 tables name tblcart and tblorderdetail:
I just show some fields in these two tables to show whats my problem:
tblCart:
ID,
CartID,
Barcode,
and tblOrderDetail:
ID,
CartID,
IsCompleted
Barcode
when someone save an order, before he confirms his request,one row temporarily enter into the tblCart,
then if he or she confirms his request another row will be inserted into the tblOrderDetail ,
Now I wanna not to show the rows that is inserted into tblOrderDetailed(showing just temporarily rows which there is in tblCart),
In another words, if there is rows in tblCart with cartID=1 and at the same time there is the same row with CartID= 1 in tblOrderDetail, then I dont want that Row.
All in all, Just the rows that there isnt in tblOrderDetail, and the field to realize this is CartID,
I should mention that I make Iscompleted=true, and with that either we can exclude the rows we do not want,
I did this:
var cartItems = context.tblCarts
.Join(context.tblSiteOrderDetails,
w => w.CartID,
orderDetail => orderDetail.cartID,
(w,orderDetail) => new{w,orderDetail})
.Where(a=>a.orderDetail.cartID !=a.w.CartID)
.ToList()
however it doesn't work.
one example:
tblCart:
ID=1
CartID=1213
Barcode=4567
ID=2
CartID=1214
Barcode=4567
ID=3
CartID=1215
Barcode=6576
tblOrderDetail:
ID=2
CartID=1213
Barcode=4567
IsCompleted=true
with these data it should just show the last two Row in tblCart, I mean
ID=2
CartID=1214
Barcode=4567
ID=3
CartID=1215
Barcode=6576
This sounds like a case for WHERE NOT EXISTS in sql.
roughly translated this should be something like this in LINQ:
var cartItems = context.tblCarts.Where(crt => !context.tblSiteOrderDetails.Any(od => od.CartID == crt.cartID));
If you have a navigation property on cart to reference details (I'll assume it's called Details), then:
var results=context.tblCarts.Where(c=>!c.Details.Any(d=>d.IsCompleted));
This is too tough for me guys. It's for Jeremy!
I have two tables (although I can also envision needing to join a third table) and I want to sum one field and count rows, in the same, table while joining with another table and return the result in json format.
First of all, the data type field that needs to be summed, is numeric(10,2) and the data is inserted as params['amount'].to_f.
The tables are expense_projects which has the name of the project and the company id and expense_items which has the company_id, item and amount (to mention just the critical columns) - the "company_id" columns are disambiguated.
So, the following code:
expense_items = DB[:expense_projects].left_join(:expense_items, :expense_project_id => :project_id).where(:project_company_id => company_id).to_a.to_json
works fine but when I add
expense_total = expense_items.sum(:amount).to_f.to_json
I get an error message which says
TypeError - no implicit conversion of Symbol into Integer:
so, the first question is why and how can this be fixed?
Then I want to join the two tables and get all the project names form the left (first table) and sum amount and count items in the second table. I have tried
DB[:expense_projects].left_join(:expense_items, :expense_items_company_id => expense_projects_company_id).count(:item).sum(:amount).to_json
and variations of this, all of which fails.
I would like a result which gets all the project names (even if there are no expense entries and returns something like:
project item_count item_amount
pr 1 7 34.87
pr 2 0 0
and so on. How can this be achieved with one query returning the result in json format?
Many thanks, guys.
Figured it out, I hope this helps somebody else:
DB[:expense_projects___p].where(:project_company_id=>user_company_id).
left_join(:expense_items___i, :expense_project_id=>:project_id).
select_group(:p__project_name).
select_more{count(:i__item_id)}.
select_more{sum(:i__amount)}.to_a.to_json
I want to loop thru a dbf and create word table for each record meeting the condition, and I got a one-page report with only the last rec in a single table. Look like all records are written to the same table. I tried to use n = n + 1 to place the variable as an element to the table
oTable = oDoc.tables[n]
But seems it only support numerical rather than variable ?
You have to add each table as you go, making sure to leave space in between them (because Word likes to combine tables).
You'll need something like this inside your loop:
* Assumes you start with oDoc pointing to the document,
* oRange set to an empty range at the beginning of the area where you want to add the tables,
* and that nRows and nCols give you the size of the table.
oTable = oDoc.Tables.Add(m.oRange, m.nRows, m.nCols)
oRange = oTable.Range()
oRange.Collapse(0)
oRange.InsertParagraphAfter()
oRange.Collapse(0)
After this code, you can use oTable to add the data you want to add. Then, on the next time through the loop, you're ready to add another table below the one you just filled.
I have a set set of records that I am loading from a file and the first thing I need to do is get the max and min of a column.
In SQL I would do this with a subquery like this:
select c.state, c.population,
(select max(c.population) from state_info c) as max_pop,
(select min(c.population) from state_info c) as min_pop
from state_info c
I assume there must be an easy way to do this in PIG as well but I'm having trouble finding it. It has a MAX and MIN function but when I tried doing the following it didn't work:
records=LOAD '/Users/Winter/School/st_incm.txt' AS (state:chararray, population:int);
with_max = FOREACH records GENERATE state, population, MAX(population);
This didn't work. I had better luck adding an extra column with the same value to each row and then grouping them on that column. Then getting the max on that new group. This seems like a convoluted way of getting what I want so I thought I'd ask if anyone knows a simpler way.
Thanks in advance for the help.
As you said you need to group all the data together but no extra column is required if you use GROUP ALL.
Pig
records = LOAD 'states.txt' AS (state:chararray, population:int);
records_group = GROUP records ALL;
with_max = FOREACH records_group
GENERATE
FLATTEN(records.(state, population)), MAX(records.population);
Input
CA 10
VA 5
WI 2
Output
(CA,10,10)
(VA,5,10)
(WI,2,10)