How do I modify a MySQL column to allow NULL?

mysql syntax
zmf picture zmf · Oct 17, 2008 · Viewed 414.8k times · Source

MySQL 5.0.45

What is the syntax to alter a table to allow a column to be null, alternately what's wrong with this:

ALTER mytable MODIFY mycolumn varchar(255) null;

I interpreted the manual as just run the above and it would recreate the column, this time allowing null. The server is telling me I have syntactical errors. I just don't see them.

Answer

Daniel Spiewak picture Daniel Spiewak · Oct 17, 2008

You want the following:

ALTER TABLE mytable MODIFY mycolumn VARCHAR(255);

Columns are nullable by default. As long as the column is not declared UNIQUE or NOT NULL, there shouldn't be any problems.

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