Delete rows from a data table that exists in another data table

Question

0.00/5 (No votes)

See more:

Hi All,

how to delete rows from a data table that exists in another data table without using for loop ? so if compare one by one , it slow the process.

Bcz both data table got more then 2 lakhs rows,while use for loop, it will slow the process, so any other way to remove ?

How to delete with one shot ?

What I have tried:

VB.NET

Dim dt1 As New DataTable()
dt1.Columns.Add("Name")
dt1.Rows.Add("Apple")
dt1.Rows.Add("Banana")
dt1.Rows.Add("Orange")
 
Dim dt2 As New DataTable()
dt2.Columns.Add("Name")
dt2.Rows.Add("Apple")
dt2.Rows.Add("Banana")
 
Dim rows_to_remove As New List(Of DataRow)()
For Each row1 As DataRow In dt1.Rows
    For Each row2 As DataRow In dt2.Rows
        If row1("Name").ToString() = row2("Name").ToString() Then
            rows_to_remove.Add(row1)
        End If
    Next
Next
 
For Each row As DataRow In rows_to_remove
    dt1.Rows.Remove(row)
    dt1.AcceptChanges()
Next


For example i gave 3 and 2 datas, but actually it retrieve  from database more than 2 lakhs data.

Regards,
Aravind

Posted 21-Mar-18 20:11pm

Aravindba

Updated 21-Mar-18 21:23pm

Maciej Los

v2

Add a Solution

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Maciej Los · Accepted Answer · 2018-03-21T21:22:00

No, there's no chance to remove data without using For...Next loop.
Note: you're using For...Next loop 3 times. You can short it to one loop only. How? Join tables by Name field to get common records for both tables, then remove it from dt1.

VB.NET

Dim rows_to_remove = From a In dt1.AsEnumerable() Join b In dt2.AsEnumerable() On a.Field(Of String)("Name") Equals b.Field(Of String)("Name")
	Select a
'returns:
'Apple 
'Banana

You can use Linq Except[^] method too:

VB.NET

Dim rows_to_remove = dt2.AsEnumerable.Except(dt1.AsEnumerable())
'returns:
'Apple 
'Banana

But! I'd do that on server side by using Transact SQL. See: DELETE (Transact-SQL) | Microsoft Docs[^]

SQL

DELETE 
FROM Table1 
WHERE FieldName1 IN (SELECT FieldName1 FROM Table2)