Re: perl and mysql column

First, if you want to extract and compare two columns, your query needs to select two columns. Your query is only extracting column 1.

Second, looking at your output, it appears that the problem is to follow a chain of match-ups. Thus if you find the pair "apple-bannana" you need to match it up with the pair "bannana-kite" - is that right? You can't just do this by printing out three columns, like you are doing. Instead you are going to need to organize your data to make it easy to take the value in column 2 and search for it in column 1. How to do that?

You will need two steps:

Convert the rows of the table into a hash
When you are done, with the conversion, search the hash for matching pairs and print them out.

A hash is kind of like two array columns - but it lets you search easily on one of the columns. For a tutorial, see Hash Crash Course

This looks a lot like a homework problem, so I'm not going to write out the code for you. Read the tutorial and update your post to reflect what you've learned. If you are having trouble using hashes, I'm sure many monks will be eager to help you if they see some code that shows what you've tried to do. The code makes it easier for us to see what you are stuck on.

Note: it is also possible that that this is not a Perl problem at all. This kind of match up can also be done using an SQL query: you need to alias your table and then join the column 1 of the table to column 2 of the aliased table. Select column 1 and 2 from the table and set column 3 to column 2 of the aliased table. I'll leave the actual construction of the query to you. For a brief tutorial on self joins, see SQL Join- Self-Join

Best, beth

Update: May not be a Perl problem at all

Comment on Re: perl and mysql column

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Re^2: perl and mysql column by Illuminatus (Curate) on Mar 03, 2009 at 15:22 UTC
First, if you want to extract and compare two columns, your query needs to select two columns. Your query is only extracting column 1. It's worse than this. You define 2 SQL operations, an insert and a select. You are doing the fetchrow on the insert, which is unlikely to do much of anything. Sure sounds like homework to me. If you want help: use mysql cli to display the table you want to parse, and cut/paste that to your post supply code that actually runs (but may not be doing what you want), instead of a snippet that references undefines (ie, @word), and clearly does nothing. There are many, many ways to accomplish the comparison/sorting you want. If you don't even know how to go about figuring out common elements in 2 arrays, then your issue is foundational.	[reply]

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Re^2: perl and mysql column
by Illuminatus (Curate) on Mar 03, 2009 at 15:22 UTC

First, if you want to extract and compare two columns, your query needs to select two columns. Your query is only extracting column 1.

Sure sounds like homework to me. If you want help:

use mysql cli to display the table you want to parse, and cut/paste that to your post
supply code that actually runs (but may not be doing what you want), instead of a snippet that references undefines (ie, @word), and clearly does nothing.
There are many, many ways to accomplish the comparison/sorting you want. If you don't even know how to go about figuring out common elements in 2 arrays, then your issue is foundational.

[reply]