i have a group of values like below pattern
name: color: percentage:
i need to sort this data in desc order of percentage
now i am using data-table DefaultView sort method
//declare columns
DataTable dt = new DataTable();
dt.Columns.Add("name");
dt.Columns.Add("color");
dt.Columns.Add("percentage");
//adding rows
DataRow dr = dt.NewRow();
dr["name"]="a";
dr["color"]="red";
dr["percentage"]="10.1";
dt.Rows.Add(dr);
//sorting
dt.DefaultView.Sort="percentage desc";
the problem is coming when the same number [percentage] is repeating more times
any idea where is the error?
Change this code:
dt.Columns.Add("percentage");
to this:
dt.Columns.Add("percentage", typeof(double));
As multiple people have pointed out, because you added the percentage as a string ("10.1") it's going to be sorted as a string. That means, since you're sorting in descending order, that "2" will appear above "10.1" in your sort. That's because string values are compared character by character, and "2" comes before "1" in a descending alphabetic sort.
Is that the problem you are talking about? If so, either of the other proposed solutions will work for you.
You also said "the problem is coming when the same number [percentage] is repeating more times" If you want a secondary sort column, which affects the order of records with the same primary sort column value (percentage), you have to specify one:
dt.DefaultView.Sort="percentage desc, name asc, color asc";
Related
Very new to access VBA and would love some guidance on this.
I am searching through a string and looking for a particular substring in this field. This substring would have a value based on another table, ie
order = "Reference order QQ131415"
The problem is, there is no particular pattern for order numbers. Some are 7 digits, some are 10 and some have dashes in there.
There is a table i have access too that has these order numbers though, and I guess I am trying to use that table as a dictionary.
my very very basic Access VBA code is like this
' order= Instr(1, rst![order], qst![order_id],vbBinaryCompare)'
order is the string where i have the order id i am trying to extract
order_id is the actual id from a seperate table.
Is this something that Access VBA can handle?
So i think this will help you
You're not very clear in the sentence following on from "order=" with your code. Could you clear that up.
Instr(string1, String2, [ compare ])
string1 Required. String expression being searched.
string2 Required. String expression sought.
Instr returns a Variant (number in this case) specifying the position of the first occurrence of one string within another. So it should be:
Position= InStr(1, string1, string2, 1)
So you'd now know that the ordernumber starts at position x in Order. You'd then have to do a left(Order, Len(order) -x) to extract the string.
Youd do that in a nested loop because youll have to loop through your dictionary per record in Order.
E.g.
Dim rsOrder as DAO.recordset
Dim rsOrderId as Dao.recordset
dim orderTest as integer
dim stringcapture as string
Set rsOrder = Currentdb.OpenRecordset("[SELECT STRING]")
rsOrder.Movefirst
Do until rsOrder.EOF or rsOrder.BOF
Order = rsOrder![OrderFieldName]
Set rsOrderId = Currentdb.OpenRecordSet("[SELECT STRING]")
rsOrderID.Movefirst
Do Until rsOrderID.EOF or rsOrderID.BOF
OrderID = rsOrderID![OrderIDFieldName]
orderTest = Instr(1, Order, OrderID,1)
StringCapture = left(Order, Len(order) -OrderTest)
rsOrderID.movenext
Loop
rsOrder.movenext
Loop
rsOrder.close
rsOrderID.close
Something to that affect.
I have a datatable and I need to be able to sort either asc or desc by the jobcode column. Unfortunately the column field values contain both numbers and letters like this.
HD1233
HD12333
PG2839
TP9383
I need to extract the numbers, sort numerically and then put it back. So the above would look like this in the output.
HD1233
PG2839
TP9383
HD12333
I have a piece of code which does some sort of sort which is like this ...
Dim dtOut As DataTable = Nothing
dt.DefaultView.Sort = Convert.ToString("jobcode" & Convert.ToString(" ")) & drpAscorDesc.SelectedItem.Text
dtOut = dt.DefaultView.ToTable()
Im just unable to do it properly without the letters. Any advice would be greatly appreciated.
Add another column of type Integer to your DataTable.
Iterate through all DataRows, put values into new column based on job codes in these datarows (read value -> delete all non-numeric characters -> Int32.TryParse()).
Sort by new column.
I have a MySQL table Page with 2 columns: PageID and OrderByMethod.
I also then have a Data table with lots of columns including PageID (the Page the data is on), DataName, and DataDate.
I want OrderByMethod to have one of three entries: Most Recent Data First, Most Recent Data Last, and Alphabetically.
Is there a way for me to tack an "ORDER BY" clause to the end of this query that will vary its ordering method based on the contents of the "OrderByMethod" column? For example, in this query, I would want to have the ORDER BY clause contain whatever ordering rule is stored in Page 1's OrderByMethod column.
GET * FROM `Data` WHERE `Data`.`PageID`=1 ORDER BY xxxxxx;
Maybe a SELECT clause in the ORDER BY clause? I'm not sure how that would work though.
Thanks!
select Data.*
from Data
inner join Page on (Data.PageID=Page.PageID)
where Data.PageID=1
order by
if(Page.OrderByMethod='Most Recent Data First', now()-DataDate,
if(Page.OrderByMethod='Most Recent Data Last', DataDate-now(), DataName)
);
You can probably do this with the IF syntax to generate a column that you can then order by.
SELECT *, IF(Page.OrderBy = 'Alphabetically', Data.DataName, IF(Page.OrderBy = 'Most Recent Data First', NOW() - Data.DataDate, Data.DataDate - NOW())) AS OrderColumn
FROM Data
INNER JOIN Page ON Data.PageID = Page.PageID
WHERE Page.PageID = 1
ORDER BY OrderColumn
The direction of the ordering is determined in the calculation of the data instead of specifying a direction in the ORDER BY
Can you just append the order by clause to the select statement and rebind the table on postback?
If you want to use the content of the column in Page table as an expression in ORDER BY you have to do it using prepared statements. Let say, you store in OrderByMethod something like "field1 DESC, field2 ASC" and you want this string to be used as it is:
SET #order_by =(SELECT OrderByMethod FROM Page WHERE id = [value]);
SET #qr = CONCAT(your original query,' ORDER BY ', #order_by);
PREPARE stmt FROM #qr;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
If you want the result set to be sorted based on the value of OrderByMethod , you can use IF as it was already mentioned by others, or CASE :
...
ORDER BY
CASE OrderByMethod
WHEN 'val1' THEN field_name1
WHEN 'val2' THEN field_name2
....etc
END
I have got a datatable which contains many columns in which three are main:
hotelid
dshotelid
hotelname
Some hotels contain only dshotelid, some contains only hotelid and some contain both dshotelid and hotelid.
I need sort in such way so that those hotels who got both dshotelid and hotelid should be on top and then those hotels who have got only dshotelid and at last those hotels who have got only hotelid...
Please help me to create such a sort expression.
I created this :
dtmaintable.DefaultView.Sort = "dshotelid, hotelid"
but it Is not giving me desired output.
Fields with NULL in them tend to appear at the top of sorted columns (unless the sort is in descending order) so you're probably seeing rows with both hotelid and dshotelid at the bottom, instead of the top?
How is this data table populated? If it's coming from a database query, it's a simple matter to construct an additional column (or columns) which contain(s) whatever sort key you need - be it an amalgum of other columns or some other unique identifier.
EDIT: Feb 4, 2010 - in response to your 'FilterAndSortTable' solution:
Your solution works but it's not because of the FilterAndSortTable - it's because you used a different sort order.
Originally, you used "dsohtelid, hotelid".
The second time, you used "dshotelid desc, hotelid desc".
This has the effect of putting your non-nulls at the top and nulls at the bottom, but I would dispute that this qualifies as a good solution.
Your id's are now sorted backwards - which I kind of assumed you might want to avoid, hence my suggestion of a new sort column that would respect this.
Still, if the order of id's doesn't matter then your solution is fine and you can simply stick with your original code, with the addition of 'desc', like so:
dtmaintable.DefaultView.Sort = "dshotelid desc, hotelid desc"
Of course, if anything I've said here has been of any use to you, a tick would be muchly appreciated. It would help me reach 50 rep points and finally be able to write comments. :)
i got the answer its :
datagrid1.datasource = FilterandSortTable(dtmaintable,"", "dshotelid desc, hotelid desc")
Public Shared Function FilterandSortTable(ByVal SourceTable As DataTable, ByVal strFilters As String, Optional ByVal strOrder As String = "") As DataTable
Dim Tbl As DataTable = SourceTable.Clone
Dim rows() As DataRow = SourceTable.Select(strFilters, strOrder)
For i As Integer = 0 To rows.Length - 1
Tbl.ImportRow(rows(i))
Next
Return Tbl
End Function
I want to count the number of non-null values per column in a Datatable. I could loop through the columns and use the compute function on each column, but I was wondering if there is a more efficient way to do this.
You could add a column with an expression that checks whether the rests of the columns are null, see http://msdn.microsoft.com/en-us/library/system.data.datacolumn.expression(VS.80).aspx
Then you can Compute on that column.
I think that the Compute function is quite appropriate in this context. You could use code similar to the following:
For Each col as DataColumn in myTable
Dim aggExpr as string = string.format("Count{0}", col.ColumnName)
Dim filterExpr as string = string.format("{0} IS NULL", col.ColumnName)
Dim myCount as integer = CInt(myTable.Compute(aggExpr, filterExpr))
Console.WriteLine(myCount)
Next
(Typed in here, watch for syntax)
Note that I say "similar to the following". Please add appropriate error/null value checks.