Table: silent_witness_cast
Columns: character
actor
years
series
episode_count

Question: How many Episode Counts have an Actor of liz carr?
SQL: SELECT COUNT("episode_count") FROM silent_witness_cast WHERE "actor" = 'liz carr'

Question: Which Years have a Character of dr trevor stewart?
SQL: SELECT "years" FROM silent_witness_cast WHERE "character" = 'dr trevor stewart'

Question: Which Series has an Actor of tom ward?
SQL: SELECT "series" FROM silent_witness_cast WHERE "actor" = 'tom ward'