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How do I modify a MySQL column to allow NULL?
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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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Alter Table Add Column Syntax
I'm trying to programmatically add an identity column to a table Employees. Not sure what I'm doing wrong with my syntax.
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Difference between this and self in self-type annotations?
In various Scala literature I see some self-type annotations using "this" and others using "self":
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How do you push just a single Git branch (and no other branches)?
...rking on a local git repository. There are two branches, master and feature_x .
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Differences between utf8 and latin1
what is the difference between utf8 and latin1?
2 Answers
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How to force a view refresh without having it trigger automatically from an observable?
Note: this is mostly for debugging and understanding KnockoutJS.
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differences between 2 JUnit Assert classes
The JUnit framework contains 2 Assert classes (in different packages, obviously) and the methods on each appear to be very similar. Can anybody explain why this is?
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How do I set a column value to NULL in SQL Server Management Studio?
How do I clear the value from a cell and make it NULL?
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How do I convert an interval into a number of hours with postgres?
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answered Jun 4 '09 at 19:23
Magnus HaganderMagnus Hagander
19.6k33 gold badges4848 silver badges4141 bronze badges
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How can I define a composite primary key in SQL?
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Just for clarification: a table can have at most one primary key. A primary key consists of one or more columns (from that table). If a primary key consists of two or more columns it is called a composite primary key. It is de...