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copied!<p>(your code is missing an <code>INSERT</code> keyword) On my version of MySQL (5.5), these are my results</p> <pre><code>drop table if exists test_table; create table test_table (number int); insert into test_table (number) values (1),(2),(3),(4); select @test := number from test_table order by rand() limit 1; # selects a random number from 1 - 4 select @test; </code></pre> <p>Results</p> <pre><code>3,4,3,1,4,3,4,3,1,3 </code></pre> <p>However, if you order by rand(now()) and do it quickly, it will stick at 4....3....2....4... because it is no longer <code>random</code>, you have given it a specific seed.</p> <p>If you run it with <strong>order by rand(1), the answer is ALWAYS the same</strong>, because you have asked it to seed based on 1 consistently.</p> <p><hr> To see what RAND() produces (which is what is used to sort the rows), check out this query:</p> <pre><code>select rand() from ( select 1 union all select 2 union all select 1 union all select 2 union all select 2 ) x; </code></pre> <p>Run it many times. Then swap for rand(now()) and run it many times quickly. Then swap for rand(1) and run again.</p> <p><hr> To see how this actually affects your query, just remove the ORDER BY and see the magic happening.</p> <pre><code>select @test := number, rand(2) from test_table order by rand(2) </code></pre> <p>Change rand(2) to rand(1) or just rand() <em>(remember to change in both places)</em>. Watch the 2 columns closely. As for how <code>@test :=</code> works, it <em>does</em> set it to the first row. BUT, it continues to set it for <em>EVERY</em> row, and ends up with the value set at the last row encountered.</p>

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