现要查找缺少学习成绩(G)的学生学号(Sno)和课程号(Cno)，相应的SQL语句 SELECT Sno，Cno FROM SC WHERE 中WHERE后正确的条件表达式是（ ）
A: G=0
B: G<=0
C: G=NULL
D: G IS NULL
A: G=0
B: G<=0
C: G=NULL
D: G IS NULL
举一反三
- 查询所有有成绩的学生学号和课程号。正确的SELECT语句是（）。 A: Select sno , cno from sc where grade < > null B: Select sno as 学号, cno as 课程号 from sc where grade is not null C: Select sno , cno from sc where grade !=‘ ’ D: Select sno , cno from sc where grade is not null
- 下列SQL语句中，________可以在“学生-课程”数据库中实现“查询所有有成绩的学生学号和课程号”。 A: SELECT Sno，Cno FROM SC WHERE Grade <> NULL B: SELECT Sno，Cno FROM SC WHERE Grade NOT NULL C: SELECT Sno，Cno FROM SC WHERE Grade >0 D: SELECT Sno，Cno FROM SC WHERE Grade IS NOT NULL
- 现要从SC表中查找缺少学习成绩(G)的学生学号(S#)和课程号(C#)，正确的SQL是 A: SELECT S#，C# FROM SC WHERE G=0 B: SELECT S#，C# FROM SC WHERE G<=0 C: SELECT S#，C# FROM SC WHERE G=NULL D: SELECT S#，C# FROM SC WHERE G IS NULL
- 现要从SC表中查找缺少学习成绩(G)的学生学号(S#)和课程号(C#),正确的SQL是( ). A: SELECT S B: ,C C: FROM SC WHERE G=NULL D: SELECT S E: ,C F: FROM SC WHERE G IS NULL G: SELECT S H: ,C I: FROM SC WHERE G=0 J: SELECT S K: ,C L: FROM SC WHERE G<=0
- “查询没有学习成绩的学生的学号和课程号”的SQL语 句是( ) (2.0) A: SELECT sno,cno FROM SC WHERE grade = NULL B: SELECT sno,cno FROM SC WHERE grade IS ' ' C: SELECT sno,cno FROM SC WHERE grade IS NULL D: SELECT sno,cno FROM SC WHERE grade = ' '