[Query Efficiency]

Sample Table

| id    |  date            | time      | ref  

|  0    |    10/10/10   | 9:51      |    2

|  1    |    10/10/10   | 9:52      |    2

|  2    |    10/10/10   | 9:53      |    4

|  3    |    10/10/11   | 9:54      |    3

|  4    |    10/10/11   | 9:55      |    4

|  5    |    10/10/11   | 9:56      |    2

 

I need to get each row where ref != id and then get the row where date, time is greatest.

 

Example output

| id    |  date            | time       | ref  

|  2    |    10/10/10   |  9:53      |    4

|  5    |    10/10/11   |  9:56      |    2

 

The results have ref != id and other rows where ref != id are eliminated because they have lesser values in date, time.

 

What is the best way to do this

[Getting every xth row's id where column=0]

thanks, I thought you could do that, but I\'m new to MySQL and wording questions can be hard (especially when looking through help files). Well, I want every 25th row, so at the end of those queries, LIMIT 25, * or LIMIT 25, 100?

[Getting every xth row's id where column=0]

meh...there are no gaps in the id, however, I don\'t want to get entries from the list where the level value is not 0. Is there no way using PHP/MySQL to just access the 25th returned row from the query:

 

SELECT * FROM table WHERE level=0

 

??¿?

[Getting every xth row's id where column=0]

I have a small database with a bunch of entries. Some entries have a value of 0 for a column \'level\', others have different values. Every row has a unique id. I need to access the id to every 25th row with a level value of 0. I\'m confused as how to accomplish this.

 

SELECT * FROM table WHERE level=0

 

then a loop to go through each one, storing the id of every 25th one in an array, but that seems a little excessive, is there an easier way to do this?