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POHow can I count all the records in the both tables in a 1:n relationship in 1 query?
 

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  1. POHow can I count all the records in the both tables in a 1:n relationship in 1 query?
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    <p>I'm guessing this a fairly easy question, but I've run into this problem a number of times and I can't find a solution either through searching (maybe I don't know what to search for) or trial and error.</p> <p>I have the following table structure and data:</p> <pre><code>CREATE TABLE `table_a` ( `id` int(11) NOT NULL auto_increment, `table_b_id` int(11) NOT NULL, `field` varchar(10) NOT NULL, PRIMARY KEY (`id`), KEY `table_b_id` (`table_b_id`) ); INSERT INTO `table_a` VALUES(1, 1, 'test 1'); INSERT INTO `table_a` VALUES(2, 1, 'test 2'); INSERT INTO `table_a` VALUES(3, 0, 'test 3'); CREATE TABLE `table_b` ( `id` int(11) NOT NULL auto_increment, `name` varchar(10) NOT NULL, PRIMARY KEY (`id`) ); INSERT INTO `table_b` VALUES(1, 'value 1'); INSERT INTO `table_b` VALUES(2, 'value 2'); </code></pre> <p>As you can see, id 2 in <code>table_b</code> is not used in <code>table_a</code> and id 3 in <code>table_a</code> has a value of 0 for <code>table_b_id</code>. What I want to do is retrieve a count of the number of times each value in b is used in <code>table_a</code>, including 2 from <code>table_b</code> and count of all the values not in <code>table_b</code>.</p> <p>I have come up with the following query:</p> <pre><code>SELECT b.name, COUNT(a.id) AS number FROM table_a AS a LEFT JOIN table_b AS b ON (b.id = a.table_b_id) GROUP BY a.table_b_id </code></pre> <p>But it obviously only returns the following:</p> <pre><code>name number ----------------- null 1 value 1 2 </code></pre> <p>How can I get the following, with only SQL:</p> <pre><code>name number ----------------- null 1 value 1 2 value 2 0 </code></pre> <p>I am using MySQL. I'm guessing the answer is simple.</p> <p><strong>Edit:</strong> Is there no other way other than a union'd query?</p>
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