Table: fa_cup_1987_88
Columns: tie_no
home_team
score
away_team
date

Question: What is the Tie number of when Wigan Athletic was the away team?
SQL: SELECT "tie_no" FROM fa_cup_1987_88 WHERE "away_team" = 'wigan athletic'

Question: Name the team with a tie number of 6.
SQL: SELECT "date" FROM fa_cup_1987_88 WHERE "tie_no" = '6'