7、ht(left(S,4),2)C.Left(Right(S,5),2) D.以上都可以19.某数据库表中有一“工作时间”字段,查找92年参加工作的职工记录准则。A.Betweeen #92-01-01# and #92-12-31#B.Betweeen "92-01-01" and "92-12-31"C.Betweeen "92.01.01" and "92.12.31"D.#92-01-01# and #92-12-31#20.下列SELECT语句语法正确的是。A.SELECT * FROM "教师表"