单项选择题
在MySQL 中，语句：DELETE FROM Employee 的作用是（）。
A.删除当前数据库中整个Employee 表，包括表结构
B.删除当前数据库中Employee 表内的所有行
C.由于没有WHERE 子句，因此不删除任何数据
D.删除当前数据库中Employee 表内的当前行
相关考题
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单项选择题
在MySQL 中，查询姓名不是NULL 的语法正确的是（）。
A.WHERE NAME ＜＞NULL
B.WHERE NAME NOT IS NULL
C.WHERE NAME IS NOT NULL
D.WHERE NAME !=NULL -
单项选择题
已知某MySQL 数据库中，有表及其字段如下：Employee（员工）表，字段：ID（标识，主键）、Name（姓名）、DepartmentID（班级标识，外键）Department（部门）表，字段：ID（标识，主键）、Name（名称）要查询各部门人数（包括空部门），可以使用的查询语句是（）。
A.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department RIGHT JOIN Employee WHERE Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID
B.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department RIGHT JOIN Employee ON Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID
C.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department LEFT JOIN Employee WHERE Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID
D.SELECT Department.Name，COUNT（Employee.ID）’班级人数’FROM Department LEFT JOIN Employee ON Department.ID =Employee.DepartmentID GROUP BY Department.Name，Employee.DepartmentID -
单项选择题
已知某MySQL 数据库中，有表及其字段如下：Employee（员工）表，字段：ID（标识，主键）、Name（姓名）、DepartmentID（班级标识，外键）Department（部门）表，字段：ID（标识，主键）、Name（名称）要查询所有空部门，可以使用的查询语句是（）。
A.SELECT。FROM Department LEFT JOIN Employee ON Department.ID =Employee.DepartmentID AND Employee.DepartmentID =NULL
B.SELECT。FROM Department LEFT JOIN Employee WHERE Department.ID =Employee.DepartmentID AND Employee.DepartmentID IS NULL
C.SELECT。FROM Department LEFT JOIN Employee ON Department.ID =Employee.DepartmentID WHERE Employee.DepartmentID IS NULL
D.SELECT。FROM Department LEFT JOIN Employee ON Department.ID =Employee.DepartmentID AND Employee.DepartmentID IS NULL
