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can not add the NOT NULL constraint
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can not add the NOT NULL constraint
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I have a table called Person in MySQL. There is a column called username. I want to add NOT NULL constraint to this column using the following:
ALTER TABLE Person MODIFY username VARCHAR(32) NOT NULL;
But it failed and reported error as:
Error Code: 1265. Data truncated for column 'username' at row 1
Why can't I change this column to be NOT NULL?
Is it possible that you already have NULL values for username stored in your table? Then you would get an error as you are creating an inconsistency within your table.
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mysql
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