Beefy Boxes and Bandwidth Generously Provided by pair Networks
P is for Practical
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Another idea that might be worth trying is a subquery:
select count(*) from theTable where column1 in (select column1 from theTable where column2 = 123) and column2 = 124
But the other suggestion would probably scale better for bigger groups of attributes.

Update: By the way, practically everyone who answered is giving you the wrong impression about indexes. Sometimes sequential scans are faster than using indexes, for example if the attribute being tested is a match for a large percentage of the records. That's what the query optimizer is supposed to do on a query-by-query basis: decide whether to use the indexes or not, and in what sequence. In the subquery I suggested above, the optimizer might not be smart enough to do it, so you might have to create the query such that the smallest subset will be selected by the inner query.


In reply to Re^2: Does DBI handle table alias? by tall_man
in thread Does DBI handle table alias? by punch_card_don

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others imbibing at the Monastery: (4)
As of 2022-08-07 18:37 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found

    Notices?