In the first query, mysqld could get all the information it
needed from table a from the index file.
In the second query, it needed to read the data file to get all
the columns, and determined that using an index would not gain
any speed. From the 3 reow returned, I woul guess that you
don't hav
Hi,
For such small tables, does it matter.
MySQL will optimise queries the best way it thinks it can. In this case, in
the first query, only the index file for student_info3 will be used, so
that might have a bearing.
In the second query, where all columns from the student table are requested
w
