Merge two tables without shifting columns

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Hi,

I have tried to Merge two DataTable objects with the method Merge and it seems that it behaves this way:

A = |col1|col2|
    |a1  |b1  |
    |a2  |b2  |
    |a3  |b3  |
    |a4  |b4  |

B = |col3|col4|
    |c1  |d1  |
    |c2  |d2  |
    |c3  |d3  |
    |c4  |d4  |

A.Merge(B) gives the following result:

|col1|col2|col3|col4|
|a1  |b1  |    |    |
|a2  |b2  |    |    |
|a3  |b3  |    |    |
|a4  |b4  |    |    |
|    |    |c1  |d1  |
|    |    |c2  |d2  |
|    |    |c3  |d3  |
|    |    |c4  |d4  |

What I want to have is:

|col1|col2|col3|col4|
|a1  |b1  |c1  |d1  |
|a2  |b2  |c2  |d2  |
|a3  |b3  |c3  |d3  |
|a4  |b4  |c4  |d4  |

In my researches, I could find different solutions such as creating empty columns, browsing rows and adding them one by one but first, this is cannot be a good way in term of performance.

Can any one help with this?

Posted 11-Oct-13 0:52am

Mehdi_S

Updated 11-Oct-13 0:55am

André Kraak

v3

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Mike Meinz 11-Oct-13 8:07am

Your desired result shows a join not a merge. In your example, there does not appear to be a "key" that links rows in table A to a corresponding row in table B. You need a common "key" to create a result set as shown in your example.

Mehdi_S 11-Oct-13 9:07am

Yeah, I have explored that solution but what if I don't need a key? I just need to add columns even if I will end up missing rows?

Mike Meinz 11-Oct-13 9:55am

See Solution 1.
Get one row from Table A (If no rows left, put NULL into variables).
Get one row from Table B (If no rows left, put NULL into variables).
Add new row to Table C using variables.
Repeat until done with both Table A and Table B.

Mehdi_S 11-Oct-13 10:09am

yeah but imagine you have like 1000 rows and 300 columns to merge or bigger. the lopp treating one by one would consume time

Member 10266297 11-Oct-13 10:15am

look my dear you have to start with the following way and when you find better way move to it but till now you don't have a way to implement so don't wast you time implement the below and search for better..

Mehdi_S 14-Oct-13 9:08am

Well, that's what I did. but I'm posting this question to have better ideas :)

Mike Meinz 11-Oct-13 11:20am

Of course, it will take time. If you don't want to do it this way, redesign the application so it does not have to be done.

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Member 10266297 · Answer 1 · 2013-10-11T02:47:00

create new datatable that is made up of the four columns then insert the rows from both old table...it is so easy like this way:

C#

DataTable dt = new DataTable("ab");
dt.Columns.Add("col2");
dt.Columns.Add("col2");
dt.Columns.Add("col3");
dt.Columns.Add("col4");

DataRow dr = dt.NewRow();
dr["col1"] = "first value in col1 from table A"
dr["col2"] = "first value in col2  from table A"
dr["col3"] = "first value in col3 from table B"
dr["col4"] = "first value in col4 from table B"

dt.Rows.Add(dr);

for sure you have to add the using loops not like that but i am giving you an example

Rakesh Meel · Answer 2 · 2013-10-11T03:21:00

Solution 2

visit here..

Merging Cells in table[^]

Posted 11-Oct-13 3:21am

Rakesh Meel