|
Posted by lark on July 5, 2007, 9:50 am
Please log in for more thread options
McMurphy wrote:
> I have a single table which I would like to search on a unique column
> varchar(15) that may have some nulls. Employee social club member no,
> some employees have a number and others don't. Those that do have a number
> will all have a unique number.
>
> I had added an index using:
> ALTER TABLE employees ADD INDEX(emp_socialclubno);
>
> However when I run:
> mysql> explain select employeeid from employees where
> emp_socialclubno=103833988;
>
+----+-------------+------------+------+---------------+------+---------+------+--------+-------------+
> | id | select_type | table | type | possible_keys | key | key_len |
> ref | rows | Extra |
>
+----+-------------+------------+------+---------------+------+---------+------+--------+-------------+
> | 1 | SIMPLE | properties | ALL | emp_socialclubno | NULL | NULL |
> NULL | 170361 | Using where |
>
+----+-------------+------------+------+---------------+------+---------+------+--------+-------------+
> 1 row in set (0.00 sec)
>
> So this indicates that even though the emp_socialclubno column has an index
> it is not being used when this column is searched ?
>
> Is this right or am I missing something ?
>
> Thanks in advance...
looks like your query is for table employees but the explain is run on
properties. these are two different tables!!!
| 
XML Sitemap