建立一个学生信息表student,要求它由学号sno,姓名sname,性别sex,年龄age,4个属性组成,其学号属性惟一,学号、姓名字段不能为空。下列语句正确的是
A.CREATE TABLE student (sno char(5) NOT NULL sname char(8) NOT NULL sex char(1) age in;
B.CREATE TABLE student (sno char(5) NOT NULL UNIQUE sname char(8) sex char(1) age in;
C.CREATE TABLE (sno char(5) NOT NULL UNIQUE sname char(8) NOT NULL sex char(1)age in;
D.CREATE TABLE student (sno char(5) NOT NULL UNIQUE sname char(8) NOT NULL sex char(1) age in;