You need to use two tables,
consultant
consultant_id | consultant_name | otherdetails ....
availability
consultant_id | date_available
Date would look like
consultant
1 | James T Kirk
2 | Jean Luc Picard
availability
1 | 2003-06-24
1 | 2003-06-25
1 | 2003-06-27
2 | 2003-06-23
2 | 2003-06-25
2 | 2003-06-26
SELECT date_available FROM availability WHERE consultant_id=2
will give the dates for Jean Luc.
hth