where-clause - Sql在WHERE子句中选择空值和非空值

Question

我正在尝试运行一个使用 WHERE 子句从表中选择值的查询，该查询只返回所有条件都有值的行，我是否要返回同样为空的值？

     Language Table                            Students Table
 ID    Language                        ID      Student      LanguageID
  1     English                         1        Joe
  2     Spanish                         2        Mike          1

运行查询，例如

Select student.ID , Student.Student , Language.language 
FROM 
    Students, Language 
WHERE 
    student.LanguageID = Language.id 

查询只为学生麦克返回一行我想返回所有学生，即使语言设置为空。

Answer 1

你想要这样的东西:

select
  student.id, student.student, language.language
from
  student left join language
      on student.languageid = language.languageid