MySQL - 游标在存储过程中不起作用

Question

我看到之前有人问过这个问题，但没有提供答案。

我正在使用游标来解析 SELECT 语句返回的数据。但是，与在命令行中运行 SELECT 语句相比，它不会返回我期望的数据。

Broker                  Year    Month   Total
Houlder Insurance           2011    10  1
Houlder Insurance           2011    11  1
Houlder Insurance           2011    12  1
Incepta                 2012    6   4
Incepta                 2012    7   6
Incepta                 2012    8   4
Kay International Plc   2011    10  4
Kay International Plc   2011    11  5
Kay International Plc   2011    12  2
Kay International Plc   2012    1   1
Kay International Plc   2012    2   1
Kay International Plc   2012    4   4
Kay International Plc   2012    5   6
Kay International Plc   2012    6   2
Kay International Plc   2012    7   1
Kay International Plc   2012    8   1
Miles Smith                 2011    12  3
Miles Smith                 2012    2   1
Miles Smith                 2012    4   1
Miles Smith                 2012    5   6
Miles Smith                 2012    6   1
Miles Smith                 2012    7   2
Miles Smith                 2012    8   2

当我运行下面的存储过程代码时，似乎只返回与经纪人“Kay International”和“Incepta”有关的记录!这个问题有解决办法吗？

    CREATE DEFINER = 'root'@'localhost'
PROCEDURE src_survey.PopulateReportMonthSurveySubmitted()
BEGIN DECLARE broker    TEXT;
  DECLARE yy        INT;
  DECLARE jan       INT;
  DECLARE feb       INT;
  DECLARE mar       INT;
  DECLARE apr       INT;
  DECLARE may       INT;
  DECLARE jun       INT;
  DECLARE jul       INT;
  DECLARE aug       INT;
  DECLARE sep       INT;
  DECLARE toct      INT;
  DECLARE nov       INT;
  DECLARE tdec      INT;

  DECLARE db_broker TEXT;
  DECLARE db_year   INT;
  DECLARE db_month  INT;
  DECLARE db_total  INT;

  DECLARE eof       INT;
  DECLARE cur1 CURSOR FOR SELECT b.company_name AS 'Broker'
                               , year(submit_date_time) AS 'Year'
                               , month(submit_date_time) AS 'Month'
                               , count(*) AS 'Total'
                          FROM
                            survey_request a
                          JOIN survey d
                          ON d.src_reference = a.src_reference
                          JOIN contacts_companies b
                          ON b.reference = a.broker_company_reference
                          JOIN src_status c
                          ON c.reference = a.src_status_reference
                          WHERE
                            underwriter_company_reference = 73
                          GROUP BY
                            broker
                          , year
                          , month
                          ORDER BY
                            broker
                          , year
                          , month;
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET eof = 1;

  SET broker = '';
  SET yy = 0;
  SET jan = 0;
  SET feb = 0;
  SET mar = 0;
  SET apr = 0;
  SET may = 0;
  SET jun = 0;
  SET jul = 0;
  SET aug = 0;
  SET sep = 0;
  SET toct = 0;
  SET nov = 0;
  SET tdec = 0;

  TRUNCATE TABLE reportmonthsurveysubmitted;
  OPEN cur1;
  SET eof = 0;

  WHILE eof = 0
  DO
    FETCH cur1 INTO db_broker, db_year, db_month, db_total;
    IF broker <> db_broker THEN
      SET broker = db_broker;
      SET yy = 0;
    END IF;
    IF yy <> db_year THEN
      IF yy <> 0 THEN
        INSERT INTO reportmonthsurveysubmitted VALUES (0, broker, yy, jan, feb, mar, apr, may, jun, jul, aug, sep, toct, nov, tdec);
      END IF;
      SET yy = db_year;
      SET jan = 0;
      SET feb = 0;
      SET mar = 0;
      SET apr = 0;
      SET may = 0;
      SET jun = 0;
      SET jul = 0;
      SET aug = 0;
      SET sep = 0;
      SET toct = 0;
      SET nov = 0;
      SET tdec = 0;
    END IF;
    CASE db_month
    WHEN 1 THEN
      SET jan = db_total;
    WHEN 2 THEN
      SET feb = db_total;
    WHEN 3 THEN
      SET mar = db_total;
    WHEN 4 THEN
      SET apr = db_total;
    WHEN 5 THEN
      SET may = db_total;
    WHEN 6 THEN
      SET jun = db_total;
    WHEN 7 THEN
      SET jul = db_total;
    WHEN 8 THEN
      SET aug = db_total;
    WHEN 9 THEN
      SET sep = db_total;
    WHEN 10 THEN
      SET toct = db_total;
    WHEN 11 THEN
      SET nov = db_total;
    WHEN 12 THEN
      SET tdec = db_total;
    END CASE;

  END WHILE;
  CLOSE cur1;

  INSERT INTO reportmonthsurveysubmitted VALUES (0, broker, yy, jan, feb, mar, apr, may, jun, jul, aug, sep, toct, nov, tdec);

END

Answer 1

您的 while 循环有问题。如果您将跟踪，那么您将了解到在 while 循环中没有为“Houlder insurance”触发插入查询。

第一次 yy = 0，在设置 broker = db_broker 和 yy = 0 之后。然后，IF yy <> db_year THEN评估为 TRUE，因此它将检查 yy <> 0，它是，因此评估为 FALSE。然后它设置 yy = db_year，因此 yy 变为 2011。第二次，broker <> db_broker是假的，所以它不会去进一步检查，然后第三条记录也去。现在，当第四条记录出现在“Incepta”时，broker <> db_broker计算结果为 TRUE，因为经纪人有“Houlder insurance”并且 db_broker 有“Incepta”，所以经纪人持有“Incepta”并且 yy = 0。接下来，yy <> db_year yy = 0 且 db_year 为 2012 时计算为 TRUE。下一个条件 yy <> 0 为 FALSE，因此这次也未执行插入，因此它作为一个整体完全跳过了“Houlder insurance”记录。

修改后的步骤如下

 CREATE DEFINER = 'root'@'localhost'
PROCEDURE src_survey.PopulateReportMonthSurveySubmitted()
BEGIN DECLARE broker    TEXT;
  DECLARE yy        INT;
  DECLARE jan       INT;
  DECLARE feb       INT;
  DECLARE mar       INT;
  DECLARE apr       INT;
  DECLARE may       INT;
  DECLARE jun       INT;
  DECLARE jul       INT;
  DECLARE aug       INT;
  DECLARE sep       INT;
  DECLARE toct      INT;
  DECLARE nov       INT;
  DECLARE tdec      INT;

  DECLARE db_broker TEXT;
  DECLARE db_year   INT;
  DECLARE db_month  INT;
  DECLARE db_total  INT;

  DECLARE eof       INT;
  DECLARE cur1 CURSOR FOR SELECT b.company_name AS 'Broker'
                               , YEAR(submit_date_time) AS 'Year'
                               , MONTH(submit_date_time) AS 'Month'
                               , COUNT(*) AS 'Total'
                          FROM
                            survey_request a
                          JOIN survey d
                          ON d.src_reference = a.src_reference
                          JOIN contacts_companies b
                          ON b.reference = a.broker_company_reference
                          JOIN src_status c
                          ON c.reference = a.src_status_reference
                          WHERE
                            underwriter_company_reference = 73
                          GROUP BY
                            broker
                          , YEAR
                          , MONTH
                          ORDER BY
                            broker
                          , YEAR
                          , MONTH;
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET eof = 1;

  SET broker = '';
  SET yy = 0;
  SET jan = 0;
  SET feb = 0;
  SET mar = 0;
  SET apr = 0;
  SET may = 0;
  SET jun = 0;
  SET jul = 0;
  SET aug = 0;
  SET sep = 0;
  SET toct = 0;
  SET nov = 0;
  SET tdec = 0;

  TRUNCATE TABLE reportmonthsurveysubmitted;
  OPEN cur1;
  SET eof = 0;

  WHILE eof = 0
  DO
    FETCH cur1 INTO db_broker, db_year, db_month, db_total;
    IF broker <> db_broker THEN
    IF yy <> 0 THEN
        INSERT INTO reportmonthsurveysubmitted VALUES (0, broker, yy, jan, feb, mar, apr, may, jun, jul, aug, sep, toct, nov, tdec);
    END IF;
    SET broker = db_broker;
    SET yy = 0;
    END IF;
    IF yy <> db_year THEN
    IF yy <> 0 THEN
        INSERT INTO reportmonthsurveysubmitted VALUES (0, broker, yy, jan, feb, mar, apr, may, jun, jul, aug, sep, toct, nov, tdec);
    END IF;

      SET yy = db_year;
      SET jan = 0;
      SET feb = 0;
      SET mar = 0;
      SET apr = 0;
      SET may = 0;
      SET jun = 0;
      SET jul = 0;
      SET aug = 0;
      SET sep = 0;
      SET toct = 0;
      SET nov = 0;
      SET tdec = 0;
    END IF;

    CASE db_month
    WHEN 1 THEN
      SET jan = db_total;
    WHEN 2 THEN
      SET feb = db_total;
    WHEN 3 THEN
      SET mar = db_total;
    WHEN 4 THEN
      SET apr = db_total;
    WHEN 5 THEN
      SET may = db_total;
    WHEN 6 THEN
      SET jun = db_total;
    WHEN 7 THEN
      SET jul = db_total;
    WHEN 8 THEN
      SET aug = db_total;
    WHEN 9 THEN
      SET sep = db_total;
    WHEN 10 THEN
      SET toct = db_total;
    WHEN 11 THEN
      SET nov = db_total;
    WHEN 12 THEN
      SET tdec = db_total;
    END CASE;

  END WHILE;
  CLOSE cur1;

  INSERT INTO reportmonthsurveysubmitted VALUES (0, broker, yy, jan, feb, mar, apr, may, jun, jul, aug, sep, toct, nov, tdec);

END 

希望对你有帮助...