Use varchar or text for a dynamic field in mysql?

I am building a table that will receive different values in a field, think of a log table that the "value" field can be a number, a tiny string or a big text etc.

So I was wonderig if I should create that "value" field as Text or create two fields, one for small inputs, like date, numbers and some string and another one only for the Texts inputs.

开发者_C百科so, my question is this: Should this "value" field be a Varchar along with some other "value2" as Text or create one field Text that the mysql will manage this corretcly?

I am afraid that creating only one Text field can be a bad thing for performance.

EDIT: the number, datetime etc are going to be cast as string before insertion, thats not the point

Thanks,

Joe

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Do you know how large the largest input will be? If you impose a limit, or know how large the maximum input will be, then you could use varchar (which caps at 255 characters in versions < 5.0.3, and 65,535 in versions >= 5.0.3). Otherwise, you're probably better off with Text, since it holds significantly more (65,535*2^16-1).

As an alternative, if users are creating things that already have tables (such as adding events to a calendar), you could just put an "is_approved" column on the table and only display approved ones, or search through everything to check for duplicates.

http://dev.mysql.com/doc/refman/5.0/en/string-type-overview.html

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If there is a limit to the length of that the data stored use varchar() (as MySQL 5.0.3 varchar max length can be up to 65,535)

If there is no concrete limit then use a 'text' field type.

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The varchar field can handle the different input's that you are mentioning but as a string, not as an integer or datetime.