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(一)、根据teacher_no统计星期的上课数-创新互联


做网站、滕州网站设计，以传统方式定制建设网站，并提供域名空间备案等一条龙服务，秉承以专业、用心的态度为用户提供真诚的服务。我们深信只要达到每一位用户的要求，就会得到认可，从而选择与我们长期合作。这样，我们也可以走得更远！/>(一)、根据teacher_no统计星期的上课数

  1. -- 解法一
  2. SELECT
  3.   t1.teacher_no,
  4.   (CASE WEEK WHEN '1' THEN keshu ELSE 0 END ) 礼拜一,
  5.   (CASE WEEK WHEN '2' THEN keshu ELSE 0 END ) 礼拜二,
  6.   (CASE WEEK WHEN '3' THEN keshu ELSE 0 END ) 礼拜三
  7. FROM
  8. (
  9.     SELECT
  10.       teacher_no,
  11.       WEEK,
  12.       COUNT(1) AS keshu
  13.       FROM teach
  14.   GROUP BY teacher_no,WEEK
  15.  )t1
  16.   GROUP BY t1.teacher_no;


  19. -- 解法二 就是count()函数作用
  20. SELECT
  21.   t1.teacher_no,
  22.   (CASE WEEK WHEN '1' THEN keshu ELSE 0 END ) 礼拜一,
  23.   (CASE WEEK WHEN '2' THEN keshu ELSE 0 END ) 礼拜二,
  24.   (CASE WEEK WHEN '3' THEN keshu ELSE 0 END ) 礼拜三
  25. FROM
  26. (
  27.   SELECT
  28.   t.teacher_no,
  29.   t.WEEK,
  30.   COUNT(t.keshu) AS keshu
  31.   FROM
  32.       (
  33.       SELECT
  34.       teacher_no,
  35.       WEEK,
  36.       '1' keshu
  37.       FROM teach )t
  38.   GROUP BY teacher_no,WEEK
  39.     )t1
  40. GROUP BY t1.teacher_no
  41. ;

网页题目：(一)、根据teacher_no统计星期的上课数-创新互联
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