Question: I have a source .csv with 21 columns and a destination table with 25 columns.

Not ALL columns within the source have a home in the destination table and not all columns in the destination table come from the source.

I cannot get my CopyData task to let me pick and choose how I want the mapping to be. The only way I can get it to work so far is to load the source data to a "holding" table that has a 1:1 mapping and then execute a stored procedure to insert data from that table into the final destination.

I've tried altering the schemas on both the source and destination to match but it still errors out because the ACTUAL source has more columns than the destination or vice versa.

This can't possibly be the most efficient way to accomplish this but I'm at a loss as to how to make it work.

The error code that is returned is some variation on:

```
"errorCode": "2200",
    "message": "ErrorCode=UserErrorInvalidColumnMappingColumnCountMismatch,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=Invalid column mapping provided to copy activity: '{LONG LIST OF COLUMN MAPPING HERE}', Detailed message: Different column count between target structure and column mapping. Target column count:25, Column mapping count:16. Check column mapping in table definition.,Source=Microsoft.DataTransfer.Common,'",
    "failureType": "UserError",
    "target": "LoadPrimaryOwner"

```

Answer: 
In the sink dataset delete the columns that you don't want to be mapped.

delete the columns that are not required in the sink by selecting and then click delete button

[![delete the columns that are not required in the sink by selecting and then click delete button[1]](https://i.stack.imgur.com/HaGTe.png)

In order for the copy to work smoothly.

1.The source dataset should have all the columns in the same sequence.  

2. All the columns selected in the sink dataset have to be mapped.
It seems that you were trying to extract the 16 columns from the source table to target table. If your target is Sql Server or Azure Sql DB, you can try the following settings:

* Set the source structure as 21 columns in csv file.
* Set the column mapping with 16 columns mapping as your wanted data.
* Set the target structure as 16 columns, which has the same name and order in the column mapping definition.