用mysql 写一个存储过程有一个7个数的数组字符串11121914151612计算回归线的斜率

首先，我们需要将给定的字符串转换为数组，这可以通过使用MySQL内置的SUBSTRING_INDEX()和CONVERT()函数来实现。我们将字符串按逗号分隔，并将每个子字符串转换为数字类型。然后，我们可以使用回归线的公式计算斜率：

CREATE PROCEDURE calculate_slope(IN array_string VARCHAR(100), OUT slope FLOAT)
BEGIN
  DECLARE arr_length INT;
  DECLARE x_mean FLOAT;
  DECLARE y_mean FLOAT;
  DECLARE x_y_mean FLOAT;
  DECLARE x_squared_mean FLOAT;
  DECLARE x_values FLOAT[];
  DECLARE y_values FLOAT[];
  DECLARE i INT DEFAULT 1;
  
  -- convert string to array
  SET arr_length = LENGTH(array_string) - LENGTH(REPLACE(array_string, ',', '')) + 1;
  WHILE i <= arr_length DO
    SET x_values[i] = CONVERT(SUBSTRING_INDEX(SUBSTRING_INDEX(array_string, ',', i), ',', -1), FLOAT);
    SET i = i + 1;
  END WHILE;
  
  -- calculate means
  SET i = 1;
  SET x_mean = 0;
  SET y_mean = 0;
  WHILE i <= arr_length DO
    SET y_values[i] = i;
    SET x_mean = x_mean + x_values[i];
    SET y_mean = y_mean + y_values[i];
    SET i = i + 1;
  END WHILE;
  SET x_mean = x_mean / arr_length;
  SET y_mean = y_mean / arr_length;
  
  -- calculate x*y and x^2 means
  SET i = 1;
  SET x_y_mean = 0;
  SET x_squared_mean = 0;
  WHILE i <= arr_length DO
    SET x_y_mean = x_y_mean + (x_values[i] * y_values[i]);
    SET x_squared_mean = x_squared_mean + (x_values[i] * x_values[i]);
    SET i = i + 1;
  END WHILE;
  SET x_y_mean = x_y_mean / arr_length;
  SET x_squared_mean = x_squared_mean / arr_length;
  
  -- calculate slope
  SET slope = (x_y_mean - (x_mean * y_mean)) / (x_squared_mean - (x_mean * x_mean));
END;

我们可以通过以下方式调用存储过程来计算回归线的斜率：

CALL calculate_slope('11,12,19,14,15,16,12', @slope);
SELECT @slope;

该存储过程将输出计算出的回归线斜率。