How do I modify a MySQL column to allow NULL?

zmf_13285 0
Viewed 504113

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.

alter syntax mysql
6 Answers

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.

Daniel_Spiewak_98150

Your syntax error is caused by a missing "table" in the query

ALTER TABLE mytable MODIFY mycolumn varchar(255) null;
PConroy_22870

My solution is the same as @Krishnrohit:

ALTER TABLE `table` CHANGE `column_current_name` `new_column_name` DATETIME NULL;

I actually had the column set as NOT NULL but with the above query it was changed to NULL.

P.S. I know this an old thread but nobody seems to acknowledge that CHANGE is also correct.

user_101779770
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