How to append one DataTable to another DataTable

Question

I would like to append one DataTable to another DataTable  I see the DataTable class has two methods   quot Load IDataReader  quot  and  quot Merge DataTable  quot    From the documentation  both appear to  merge  the incoming data with the existing DataTable if rows exist  I will be doing the merge in a data access layer  I could use an IDataReader and use the Load method to merge the DataTables  Or I could load a DataSet using the IDataReader  get the DataTable from the DataSet  and then use the Merge method to merge the DataTables  I was wondering if someone could tell me which is the proper method to use  Alternatively  let me know if you have a different suggestion on how to accomplish this task

User · Answer

The datatype in the same columns name must be equals   dataTable1 Merge dataTable2     After that the result is   dataTable1   dataTable1   dataTable2

User · Answer

Consider a solution that will neatly handle arbitrarily many tables     ASSUMPTION  All tables must have the same columns var tables   new List lt DataTable gt     tables Add oneTableToRuleThemAll   tables Add oneTableToFindThem   tables Add oneTableToBringThemAll   tables Add andInTheDarknessBindThem     Or in the real world  you might be getting a collection of tables from some abstracted data source     behold  a table too great and terrible to imagine var theOneTable   tables SelectMany dt   gt  dt AsEnumerable    CopyToDataTable      Encapsulated into a helper for future reuse   public static DataTable CombineDataTables params DataTable   args        return args SelectMany dt   gt  dt AsEnumerable    CopyToDataTable        Just have a few tables declared in code   var combined   CombineDataTables dt1 dt2 dt3     Want to combine into one of the existing tables instead of creating a new one   dt1   CombineDataTables dt1 dt2 dt3     Already have a collection of tables  instead of declared one by one     Pretend variable tables already exists var tables   new     dt1  dt2  dt3    var combined   CombineDataTables tables

User · Answer

Add two datasets containing datatables  now it will merge as required  DataSet ds1   new DataSet    DataSet ds2   new DataSet     DataTable dt1   new DataTable    dt1 Columns Add new DataColumn  Column1   typeof System String      DataRow newSelRow1   dt1 NewRow    newSelRow1  Column1      Select   dt1 Rows Add newSelRow1    DataTable dt2   new DataTable    dt2 Columns Add new DataColumn  Column1   typeof System String      DataRow newSelRow2   dt1 NewRow    newSelRow2  Column1      DataRow1Data       Data dt2 Rows Add newSelRow2    ds1 Tables Add dt1   ds2 Tables Add dt2    ds1 Tables 0  Merge ds2 Tables 0      Now ds1 will have the merged data

User · Answer

You could let your DataAdapter do the work   DataAdapter Fill DataTable  will append your new rows to any existing rows in DataTable

User · Answer

Merge takes a DataTable  Load requires an IDataReader - so depending on what your data layer gives you access to  use the required method  My understanding is that Load will internally call Merge  but not 100  sure about that   If you have two DataTables  use Merge

User · Answer

use loop       for  int i   0  i  lt  dt1 Rows Count  i                               dt2 Rows Add dt1 Rows i  0   dt1 Rows i  1          you have to insert all Columns

[c#] How to append one DataTable to another DataTable

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