MYSQL

Question

我有这个table:

person_id    first_name   middle_name    last_name    gender    form
P.1          John         null           null         null      form1
P.1          null         null           null         null      form1
P.1          null         R              null         null      form1
P.1          null         null           Doe          M         form1
P.2          Mary         null           null         null      form2
P.2          null         null           Jane         null      form2

如何return得到以下结果集：

person_id    first_name   middle_name    last_name    gender    form
P.1          John         R              Doe          M         form1
P.2          Mary         null           Jane         null      form2

Answer 1

http://sqlfiddle.com/#!9/85ab4/1

SELECT person_id,
  MAX(first_name), 
  MAX(middle_name), 
  MAX(last_name), 
  MAX(gender),
  form
FROM my_table
GROUP BY person_id, form

但您绝对应该更改您的数据库架构。

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