Take the tour ×  I have a table and I am always getting the data
by ordering a column. In my case, I order by datenum. However,
the selection is so slow because of the ordering.  Is it
possible to order the table after datenum. This column is
defined as unique. If defined as an index, would the selection
will be faster?  share|improve this question I like this
question because it introduces the idea of performing the ORDER
BY on a table. +1 !!! –  RolandoMySQLDBA Aug 29 '11 at 12:42 add
comment  2 Answers  up vote 5 down vote accepted   • There is no
natural, implied or intrinsic ordering to a table   • Any order
is only guaranteed by the outermost ORDER BY  If this is slow,
then you can either    • make the index covering (a UNIQUE
constraint is an index already)   • make it the clustered index
(which is covering by its nature) share|improve this answer add
comment  It is possible to perform ORDER BY on a table.  ALTER
TABLE ... ORDER BY {columns} ;  According to the MySQL
Documentation    • ORDER BY enables