How to ALTER multiple columns at once in SQL Server

If you don't want to write the whole thing yourself and change all the columns to the same datatype this can make it easier:

select 'alter table tblcommodityOHLC alter column '+name+ 'NUMERIC(18,0);'
from syscolumns where id = object_id('tblcommodityOHLC ')

You can copy and paste the output as your query

Doing multiple `ALTER COLUMN` actions inside a single `ALTER TABLE` statement is not possible.

See the `ALTER TABLE` syntax [here][1]

You can do multiple `ADD` or multiple `DROP COLUMN`, but just one `ALTER
COLUMN`.


[1]:

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As others have answered, you need multiple `ALTER TABLE` statements.
Try following:

ALTER TABLE tblcommodityOHLC alter column CC_CommodityContractID NUMERIC(18,0);
ALTER TABLE tblcommodityOHLC alter column CM_CommodityID NUMERIC(18,0);

This is **not possible**. You will need to do this one by one.
You could:

1. Create a Temporary Table with your modified columns in
2. Copy the data across
3. Drop your original table (Double check before!)
4. Rename your Temporary Table to your original name