下面变量命名是错误的，请说明原因if，3aa，#what, @name

关系模式department(code,name)、employee(code,name,sex,dept,phone),查询“研发部”的员工信息,查询结果包括code,name,sex,phone,正确的语句是() A: selectcode,name,sex,phonefromemployeewheredept=’研发部’; B: selectcode,name,sex,phonefromemployeeem,departmentdewherede.code=em.deptandde.dept=’研发部’; C: selectcode,name,sex,phonefromemployeeem,departmentdewherede.code=em.codeandde.name=’研发部’; D: Selectem.code,name,sex,phonefromemployeeem,departmentdewherede.code=em.deptandde.name=’研发部’;

代码[form action="" method="POST" ]性别：[input name="sex" type="radio" value="男" checked]男 [input type="submit" name="Submit" value="提交"][/]，运行时只点击提交而不作任何输入，关于变量$_POST["sex"]的值正确的说法是 A: $_POST["sex"]为空字符串 B: $_POST["sex"]变量不存在 C: $_POST["sex"]= "radio" D: $_POST["sex"]= "男"

在JAVA中,变量命名正确的是() A: ${student} B: 1_people C: _OK D: "name"

【多选题】下面语句可以实现查询user表中“zhangsan”的user,password,logins信息的是 A. select logins,user,password from user where name like ’%zhangsan%’; B. select user,password,logins, from user where name like ’zhangsan’; C. select password,logins,user from user where name=’zhangsan’ limit 1; D. select user,password,logins from user where name=’zhangsan’;