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Changing a column to "Is Identity = Yes" when data exists in the column.

Hello Experts,

I have imported data from Excel into MS SQL Server 2012 Express. All of the records have IDs already assigned to them. My task was and is to take the Excel data and normalize it into various tables and basically build a database. I went about this by breaking out the data into Excel sheets and manually assigning IDs to related the data together. Now that I am finished with that process I am ready to import into MS SQL Server, but I see that what I intended to be the Primary Key for each table, I cannot set the Is Identity = Yes attribute. Is that because there is already data in the table? Is there a way to do this? What is your advice for me? I suppose I could just add a new column to each table once imported and make it the Primary Key and set Identity = Yes, but I don't know if that's they best answer.

Thank you,
1 Solution
Guru JiCommented:
Check your column data type for ID you are importing from excel.

If it is varchar then you can't change it to identity column.

To change it to identity column, it should have int data type.
RiverWalkAuthor Commented:
In Excel, the column is the "number" format, but once it comes into SQL Server it is of data type, "float". I have set the decimal setting to zero in Excel, but it still comes into MS SQL Server as float. However, your comment prompted me to try something that I thought I tried before but was not sure if I really followed through with it. I thought I tried changing the field from float to int in SSMS, but I guess I did not, because I just tried it and it worked, After changing to int and saving it, then I was able to set Is Identify = Yes. Great!

I think I was afraid that changing the data type in SQL Server would drop the table and cause me to lose data. But it didn't.

Thank you!

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