如何消除SQL中的重复计算?

在MySQL中使用别名:

SELECT *, LOCATE( column, :keyword ) AS somelabel 
FROM table 
HAVING somelabel > 0 
ORDER BY somelabel

SELECT *, LOCATE( column, :keyword ) AS somelabel 
FROM table 
WHERE somelabel > 0 
ORDER BY somelabel

Jeff Ober有正确的想法,但这里有一个替代方法:

SELECT
  t.*
 ,loc.LOCATED
FROM
  table t
  INNER JOIN
  (
  SELECT
    primary_key
   ,LOCATE(column,:keyword) AS LOCATED
  FROM
    table 
  ) loc
  ON t.primary_key = loc.primary_key
WHERE loc.LOCATED > 0
ORDER BY
  loc.LOCATED