MYSQL Update all foreign key values
<p>I have two identical tables that are located in two identical databases(with different name). I want to merge these two tables, but their primary keys are used in other tables,   </p>

<p>these tables look like this:</p>

<p><strong>Table A</strong>  </p>

<pre><code>id     column1     column2    column3
___    ________    _______    ________
 1        text        text      text
 2        text        text      text
 3        text        text      text   
</code></pre>

<p><strong>Table B</strong>  </p>

<pre><code>id     column1     column2    column3
___    ________    _______    ________
 2        text        text      text
 3        text        text      text
 4        text        text      text 
</code></pre>

<p><strong>tables that are linked to Table A</strong>  </p>

<p><strong>Link A</strong>  </p>

<pre><code>id     column1     tableA_ID
___    ________    _______  
 1        text        2     
 2        text        3      
 3        text        4   
</code></pre>

<p><strong>Link B</strong>  </p>

<pre><code>id     column1     tableA_ID
___    ________    _______  
 1        text        3     
 2        text        3      
 3        text        2    
</code></pre>

<p>Please note, the tables have identical <code>id</code>'s, this means when I do the merge, I have to change the <code>id</code>'s of the second table. Remember the <em>second table's primary keys are used in other tables.</em>   </p>

<p>I wrote this query to merge the two tables:  </p>

<pre><code>INSERT INTO db_A.`Table_A`(`column2`,`column3`) 
    SELECT `column2`,`column3` FROM db_B.`Table_B`; 
</code></pre>

<p>This query will correctly copy the records of the second table to the first table.  </p>

<p>Now I want to also move the data of the tables that are linked with <code>Table B</code>, I can use the same query, but now the foreign key will not match, because the <code>ID</code> they were linked with has been changed.</p>

<p>How do I update them so that the <code>ID</code> will match again?</p>

<p><strong>NB: I do not have the ON UPDATE CASCADE constraint on those tables</strong></p>

<p>I hope this make sense, I will try to improve this question so that everyone understands it.</p>

<p><strong>Database Info</strong></p>

<pre><code>Type  : MySQL
Engine: MyISAM
</code></pre>