How to check with PHP does a SQL database already have

Posted by Dan Horvat on Stack Overflow See other posts from Stack Overflow or by Dan Horvat
Published on 2012-04-06T17:24:56Z Indexed on 2012/04/06 17:29 UTC
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php

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mysql

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database

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query

I've tried to find the answer to this question but none of the answers fit.

I have two databases, one has 15.000.000 entries and I want to extract the necessary data and store it in a much smaller database with around 33.000 entries. Both databases are open at the same time. Or at least they should be.

While having the big database open and extracting the entries from it, is it possible to check whether the value already exists in the smaller database? I just need some generic way which checks that.

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