using distinct

[jeff5656]

I want to select records with DISTINCT only records with payment_type of a certain type are displayed once:

 

$query = "select distinct payment_type  from payments ";

 

So if I have payment_types of "A", "B" and "C"

each of those 3 will only be displayed once and not repeated.  The problem is, how do I SELECT more fields from each record?  I tried

$query = "select distinct payment_type, *  from payments ";

but that didn't work.

 

[Maq]

Use GROUP BY:

$query = "SELECT * FROM payments GROUP BY payment_type";

 

Also, don't use * unless you really do need all the columns.

[The Little Guy]

Also, don't use * unless you really do need all the columns.

 

I hear that is also a good idea to list the fields in the order they are in the database skipping the ones not needed. I could be wrong but that is what I heard.

[Maq]

Also, don't use * unless you really do need all the columns.

 

I hear that is also a good idea to list the fields in the order they are in the database skipping the ones not needed. I could be wrong but that is what I heard.

Haven't heard of that, do you know for what reason(s)?

[The Little Guy]

I was told it was faster. I assume it is so MySQL doesn't have to reorder columns/data, it would just get the columns/data as is without having to reorder it.

[Maq]

I was told it was faster. I assume it is so MySQL doesn't have to reorder columns/data, it would just get the columns/data as is without having to reorder it.

Interesting.  I guess it makes sense, I'll have to check it out.

[fenway]

Yes, but not noticeably so.

 

Also, don't mix * and GROUP BY -- you'll get garbage data.

 

Selecting "more" with one of each payment type doesn't make any sense.