title: mysql procedure CONCAT error
body: <p>I want copy data to table from another table with  current month  </p>
  
  <p>This sql is ok<br>
  <code>SELECT * FROM aqi_hour where  DATE_FORMAT( date, '%Y%m' ) =  DATE_FORMAT( CURDATE( ) ,'%Y%m' )</code></p>
  
  <hr>
  
  <p>But this is not ok , execute CALL porcedureName()
  <code>create procedure porcedureName () 
  begin 
      SET @sqlstr = CONCAT(' CREATE TABLE aqi_hour_',DATE_FORMAT(now(),'%Y%m') ,' SELECT * FROM aqi_hour where ', DATE_FORMAT( date, '%Y%m' ) ,'=', DATE_FORMAT( CURDATE( ) , '%Y%m' ));
          PREPARE stmt1 FROM @sqlstr ;
          EXECUTE stmt1 ; 
  end</code></p>
  
  <p>Error message : [Err] 1054 - Unknown column 'date' in 'field list'</p>
  
  <p>Thanks!</p>