Let mysql recommend your table definition

If you have an existing table, you can have mysql tell you what it thinks the optimal definition for the table ought to be.

Like so:

select * from mytable procedure analyse();

Note the British spelling of 'analyse'.

This will return a row of results for every column in the select statement. Here's the result for an example column:

*************************** 1. row ***************************
Field_name: someschema.sometable.somecolumn
Min_value: #1 Cochran, Inc.
Max_value: ZZZ Capital Corp.
Min_length: 2
Max_length: 112
Empties_or_zeros: 0
Nulls: 0
Avg_value_or_avg_length: 24.2406
Std: NULL
Optimal_fieldtype: VARCHAR(112) NOT NULL

This will tell you the smallest, largest, and average values of every column in the table, the number of empty or null values, and a recommended definition for the column. Getting the range of a column to determine its optimal size is something I do all the time, so it's nice to have a shortcut to help you do that.

This works well with the 'show table status' command to tell you the absolute table and row sizes of your tables.