经典sql查询(一)
员工表结构如下：CREATE TABLE `emp` ( `EMPNO` int(0) NOT NULL AUTO_INCREMENT COMMENT '员工号', `ENAME` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NULL DEFAULT NULL COMMENT '员工姓名', `JOB` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_
