SQL将属性与同一表中另一行的属性进行比较

Question

Let's say I have a table of people with their names and Dates of Birth. How can I select all people's names who have greater DofB than another person while only knowing that persons name and not DofB?

Answer 1

You have some options, but I like a JOIN here.

Assuming you have a unique name field (using a unique row identifier like id is probably better):

SELECT p.name
  FROM person p
  JOIN person po
    ON po.name = :name_that_you_know
 WHERE p.dob > po.dob

This cross JOINs every person row with the row of the person that you named. The results are filtered by the date of birth comparison.

Alternatively you can perform the filter in the JOIN condition:

SELECT p.name
  FROM person p
  JOIN person po
    ON po.name = :name_that_you_know
   AND po.dob < p.dob

Answer 2

Use a simple mysql query like

SELECT a.name, b.dob FROM table a INNER JOIN table b ON b.name = 'john' AND a.dob > b.dob

Something like that

Answer 3

This will find all people with a DOB greater (or younger) than the a person you are not sure of their DOB, but know their name:

SELECT name
FROM yourTable
WHERE DOB > (SELECT DOB FROM yourTable WHERE name = 'nameyouknow');