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8.3

questions about control statements in MySQL

Asked by errang in MySQL Server, Databases Miscellaneous

Tags: control statements, MySQL

Hey,

       I just had a few quick questions about MySQL:

First, I was supposed to write a command that would update the price of a PC, if there isn't a lower priced PC with the same speed already in the table:

CREATE TRIGGER testA BEFORE INSERTION PC
   FOR EACH ROW BEGIN
     UPDATE PC SET price = NEW.price WHERE price > NEW.price OR speed > NEW.speed OR speed < NEW.speed;
   END;

I'm new to MySQL and didn't know how to use the not equals operator, so I went the safe way by checking if a value is greater or less than the new value, I'm hoping it would break if it is equal.  Am I right?

The second question I had is, I need to insert a model number into a table if the model number doesn't already exist, the table has 3 other values color, type, price, but they can be NULL for our purposes... I'm kinda lost on how to do this, I was following http://dev.mysql.com/doc/refman/5.0/en/create-trigger.html to get the other thing done, but its not very helpful on this one.  Would I write something like INSERT INTO Printer IF NEW.model# DOES NOT EXIST?

Appreciate any help on this!!!
     
[+][-]11/02/09 03:37 PM, ID: 25724923Accepted Solution

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About this solution

Zones: MySQL Server, Databases Miscellaneous
Tags: control statements, MySQL
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Solution Provided By: angelIII
Participating Experts: 1
Solution Grade: A
 
[+][-]11/02/09 03:55 PM, ID: 25725027Author Comment

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[+][-]11/02/09 04:27 PM, ID: 25725190Author Comment

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[+][-]11/02/09 04:32 PM, ID: 25725210Author Comment

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[+][-]11/02/09 05:18 PM, ID: 25725401Author Comment

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