title: Get the max length allowed in column, mysql
body: <p>i need to know how to get the max size of an specific column in mysql, the table is </p>
  
  <p>turno : </p>
  
  <pre><code>CREATE TABLE `turno` (  
  `idTurno` tinyint(4) NOT NULL,  
  `nombreTurno` varchar(20) COLLATE utf8_spanish2_ci NOT NULL,  
  `horaInicio` tinyint(4) NOT NULL,  
  `horafin` tinyint(4) NOT NULL,  
  `valorTurno` int(11) NOT NULL,  
  PRIMARY KEY (`idTurno`)) 
  ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish2_ci
  </code></pre>
  
  <p>the column : </p>
  
  <pre><code>`nombreTurno` varchar(20) COLLATE utf8_spanish2_ci NOT NULL
  </code></pre>
  
  <p>i should get : </p>
  
  <pre><code>20
  </code></pre>
  
  <p>im getting: </p>
  
  <pre><code>NULL
  </code></pre>
  
  <p>the query : </p>
  
  <pre><code>SELECT MAX( LENGTH( nombreTurno ) ) AS maxl
  FROM turno
  </code></pre>
  
  <p>hope you can help me, thank you</p>