在查询中应用IsNull,而不在查询中应用isull:
ISNULL((SELECt rc.name from ReimbursementChoice rc WHERe rc.admin_id = a.admin_id AND rc.choice_id = pe.alt_payment_choice),' ') AS 'AltReimMethod'

在查询中应用IsNull,而不在查询中应用isull:
ISNULL((SELECt rc.name from ReimbursementChoice rc WHERe rc.admin_id = a.admin_id AND rc.choice_id = pe.alt_payment_choice),' ') AS 'AltReimMethod'