MySQL多条件更新列值异常：预期更新7行仅成功1行求助

• 先确认运算符优先级（你的语句逻辑本身无歧义，但可以优化写法）
  SQL中AND优先级高于OR，你的语句实际执行逻辑和预期的两个条件组一致：

  (occupation = 'Model' AND bonus = 155.99) OR (givenname = 'Mary' AND bonus = 155.99)
  

  为了彻底避免歧义，建议手动添加括号明确分组：

  UPDATE customers
  SET bonus = 505.99
  WHERE 
    (occupation = 'Model' AND bonus = 155.99)
    OR 
    (givenname = 'Mary' AND bonus = 155.99);
  

• 重点排查浮点数值精度问题
  如果bonus是FLOAT或DOUBLE类型，这类浮点型存储的是近似值，直接用= 155.99会匹配不到实际值接近但有微小精度差异的行。可以用两种方式解决：
  方法1：范围匹配（推荐）

  UPDATE customers
  SET bonus = 505.99
  WHERE 
    (occupation = 'Model' AND bonus BETWEEN 155.989 AND 155.991)
    OR 
    (givenname = 'Mary' AND bonus BETWEEN 155.989 AND 155.991);
  

  方法2：用ROUND函数统一精度

  UPDATE customers
  SET bonus = 505.99
  WHERE 
    (occupation = 'Model' AND ROUND(bonus, 2) = 155.99)
    OR 
    (givenname = 'Mary' AND ROUND(bonus, 2) = 155.99);
  

• 先查询验证再执行更新
  先执行SELECT语句确认符合条件的行数，避免直接更新踩坑：

  SELECT COUNT(*)
  FROM customers
  WHERE 
    (occupation = 'Model' AND bonus = 155.99)
    OR 
    (givenname = 'Mary' AND bonus = 155.99);
  

  如果查询返回1行，说明数据本身只有1行符合条件；如果返回7行，再检查更新语句的执行权限或数据库事务是否未提交。

内容的提问来源于stack exchange，提问作者char