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我是子查询的新手，我认为在以下情况下我需要它们，但不知道如何继续。

我有以下查询。现在，我有两件事需要添加到查询中 =

  • 对于 CA 消费者，他们只能有 1 次车祸（car_acc），而在其他州则无关紧要。

  • 在佛罗里达州、马里兰州、新罕布什尔州和西澳州，当前投保的可能为 0（布尔值），而在其他州则只能为 1。

    SELECT Count(*),
       Avg(sl.our_cost),
       Avg(sl.purchase_price)
FROM   sold_leads AS sl
       INNER JOIN leads AS l
               ON l.id = sl.lead_id
       INNER JOIN contacts AS c
               ON c.lead_id = l.id
       INNER JOIN drivers AS d
               ON d.lead_id = l.id
WHERE  c.state IN( 'AK', 'AL', 'AR', 'AZ',
                   'CA', 'CO', 'CT', 'DC',
                   'DE', 'FL', 'GA', 'HI',
                   'IA', 'ID', 'IL', 'IN',
                   'KS', 'KY', 'LA', 'MD',
                   'ME', 'MI', 'MN', 'MO',
                   'MS', 'MT', 'NC', 'ND',
                   'NE', 'NH', 'NJ', 'NM',
                   'NV', 'NY', 'OH', 'OK',
                   'OR', 'PA', 'RI', 'SC',
                   'SD', 'TN', 'TX', 'UT',
                   'VA', 'VT', 'WA', 'WI',
                   'WV', 'WY' )
       AND l.leg = 0
       AND ( Datediff(CURRENT_DATE, d.date_of_birth) / 365 ) >= 50
       AND l.create_date >= '2012-1-1';

我将如何将这些子查询添加到我的查询中？有没有更好的方法来查找该信息？

编辑：

我应该提一下，它应该是 1 次“车祸”或“违规”。我有两张不同的表格，其中包含车祸和违规行为，因此对于 CA 居民，我只需要那些有 1 次事故或 1 次违规的人。

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2 回答 2

1

因为 , 的数据car_accidents位于violations单独的表中，所以您需要使用left join.

希望这是有道理的:-)

SELECT Count(*),
       Avg(sl.our_cost),
       Avg(sl.purchase_price)
FROM   sold_leads AS sl
       INNER JOIN leads AS l
               ON l.id = sl.lead_id
       INNER JOIN contacts AS c
               ON c.lead_id = l.id
       INNER JOIN drivers AS d
               ON d.lead_id = l.id
       LEFT JOIN 
  (SELECT ca1.driver_id, COUNT(*) AS cnt FROM car_accidents ca1 GROUP BY ca1.driver_id) ca 
               ON (c.state = 'CA' and ca.driver_id = d.id)
       LEFT JOIN 
  (SELECT v1.driver_id, COUNT(*) AS cnt FROM violations v1 GROUP BY v1.driver_id) v
               ON (c.state IN ('CA') and v.driver_id = d.id)
WHERE  c.state IN( 'AK', 'AL', 'AR', 'AZ','CA', 'CO', 'CT', 'DC',
                   'DE', 'FL', 'GA', 'HI','IA', 'ID', 'IL', 'IN',
                   'KS', 'KY', 'LA', 'MD','ME', 'MI', 'MN', 'MO',
                   'MS', 'MT', 'NC', 'ND','NE', 'NH', 'NJ', 'NM',
                   'NV', 'NY', 'OH', 'OK','OR', 'PA', 'RI', 'SC',
                   'SD', 'TN', 'TX', 'UT','VA', 'VT', 'WA', 'WI',
                   'WV', 'WY' )
       AND l.leg = 0
       AND ( Datediff(CURRENT_DATE, d.date_of_birth) / 365 ) >= 50
       AND l.create_date >= '2012-1-1'
       AND IFNULL(v.cnt,0) < 2 AND ifnull(ca.cnt.0) < 2
       AND (c.state IN ('FL','MD','NH','WA') OR c.IsInsured = 1)

note 将状态放在单独的表中会更有意义。这样，您可以将条款和条件放在该表中，并在您的联接条件中使用它们。

Table state
-----------
id : varchar(2) primary key not null
country : varchar(45) not null
max_accidents : int null
max_violations : int null
must_be_insured : boolean not null

然后您可以将查询重写为：

SELECT Count(*),
       Avg(sl.our_cost),
       Avg(sl.purchase_price)
FROM   sold_leads AS sl
       INNER JOIN leads AS l
               ON l.id = sl.lead_id
       INNER JOIN contacts AS c
               ON c.lead_id = l.id
       INNER JOIN drivers AS d
               ON d.lead_id = l.id
       INNER JOIN state s ON (s.id = c.state)
       LEFT JOIN 
(SELECT ca1.driver_id, COUNT(*) AS cnt FROM car_accidents ca1 GROUP BY ca1.driver_id) ca 
           ON (s.max_accidents IS NOT NULL AND ca.driver_id = d.id)
   LEFT JOIN 
(SELECT v1.driver_id, COUNT(*) AS cnt FROM violations v1 GROUP BY v1.driver_id) v
           ON (s.max_violations IS NOT NULL AND v.driver_id = d.id)
       AND l.leg = 0
       AND (Datediff(CURRENT_DATE, d.date_of_birth) / 365.25 ) >= 50
       AND l.create_date >= '2012-1-1'; 
       AND IFNULL(v.cnt,0) < 2 AND ifnull(ca.cnt.0) < 2
       AND (s.must_be_insured = 0 OR c.IsInsured = 1)
于 2013-01-28T17:57:03.187 回答
0

我知道它与子查询不同，但我经常用 CASE 语句解决这个“子条件”问题。您可以在 WHERE 子句的末尾添加一个：

WHERE c.state IN (...)
    AND l.leg = 0
    AND ( Datediff(CURRENT_DATE, d.date_of_birth) / 365 ) >= 50
    AND l.create_date >= '2012-1-1'
    AND CASE 
        # Identify cases where record should be excluded
        WHEN c.state = 'CA' AND c.car_acc > 1   THEN 0
        WHEN c.state NOT IN ('FL', 'MD', 'NH', 'WA') AND c.currently_insured = 1   THEN 0
        ELSE 1
    END = 1

警告：与其他过滤方法相比，我不知道这会如何影响性能。

于 2013-01-28T17:57:21.847 回答