Hi Dhananjay Singh,
Welcome to Microsoft Q&A forum and thanks for posting your query. As per the documentation, ADF copy activity doesn't support DAT file format.
There is no direct or out of box dataset for DAT Format files. But if you would like to copy the DAT file extension with a Copy activity supported data format to SQL column, what you can do is you can also use the Delimited Text Format dataset and specify the extension of the file as .DAT
file.
Once you have created the dataset, you can use the Copy Data activity in your pipeline to copy the data from the .DAT file to your SQL Server.
Here is an feature request submitted by a different user in Azure feedback forum. Please feel free to up-vote and comment on it to help increase the priority of this feature request: create a new Linked Service connector for DAT Files
Hope this info helps.
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