将MySQL查询从何处更改为左连接

我有一个查询报告星号呼叫使用情况和队列统计信息。查询当前使用MySQL WHERE子句连接表并过滤数据

以下是当前查询的外观：

SELECT 
    c.name as 'Agent',
    e.extended_number AS 'Extension',
    COUNT(ql.`time`) AS 'Total Inbound Calls',
    (SELECT 
            COUNT(1) 
    FROM
        call_history ch,
        ast_queue_mstatus qm
    WHERE
        ch.start >= (DATE_SUB(DATE(NOW()),
            INTERVAL 10050 MINUTE))
            AND ch.start <= (DATE(NOW()))
            AND ch.calltype = 'out'
            AND ch.flow = 'out'
            AND ch.extension_number = qm.membername
            AND qm.membername = e.extended_number
    GROUP BY qm.membername) AS 'Total Outbound Calls',
    FORMAT(SUM(CAST(ql.arg2 AS UNSIGNED)) / 60, 2) AS 'Total Inbound Duration',
    FORMAT(AVG(CAST(ql.arg2 AS UNSIGNED)) / 60, 2) AS 'Avg Inbound Duration',
    FORMAT(AVG(CAST(ql.arg1 AS UNSIGNED)) / 60, 2) AS 'Avg Caller Hold Time'
FROM
    ast_queue_log ql,
    ast_queue_mstatus qs,
    client c,
    extension e
WHERE
    ql.queuename = '1234'
    AND ql.`time` >= (DATE_SUB(DATE(NOW()), INTERVAL 7 DAY))
    AND ql.`time` <= (DATE(NOW()))
    AND (ql.event = 'COMPLETEAGENT'
    OR ql.event = 'COMPLETECALLER'
    OR ql.event = 'COMPLETETRANSFER')
    AND RIGHT(ql.agent, 8) = qs.membername
    AND qs.membername = e.extended_number
    AND e.client_id = c.id      
GROUP BY ql.agent
ORDER BY c.name;

我遇到的问题是，我需要为尚未收到任何入站呼叫的队列成员返回出站呼叫结果。此时，如果ast_queue_log中没有记录，那么WHERE子句将排除这些记录，这意味着标量子查询不会提取这些记录

如何更改此查询，以便从呼叫历史记录中获取所有呼叫记录，其中ast_队列_mstatus中有相应的记录

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对不起，如果这太复杂或没有足够的信息，我可以尝试简化，如果这没有意义

是时候抛弃那些旧的逗号分隔表列表，使用1992年引入的联接标准了是的：-

因为这样就可以使用左连接。对于这种连接，关系是可选的。也就是说，如果第一个表中的所有行与WHERE子句中的条件匹配，则返回它们，但是联接的表也不必有记录。 如果没有，则仍然返回一行，但字段中填充空值

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您还可以使用RIGHT JOIN，以另一种方式围绕第一个表进行连接，这是可选的。但总的来说，这更难解释。

我给出了答案，但现在我看到答案的核心——从何处移动到左连接的条件已经在标题中了。让我想知道：如果你已经知道了，为什么要问？@GolezTrol谢谢你的回答，我问这个问题的原因是我知道左join是答案，但无法理解语法和所需内容。你的回答很有帮助，我希望今天下午实施：

SELECT 
    c.name as 'Agent',
    e.extended_number AS 'Extension',
    COUNT(ql.`time`) AS 'Total Inbound Calls',
    (SELECT 
        COUNT(1) 
    FROM
        call_history ch
        INNER JOIN ast_queue_mstatus qm 
          ON qm.membername = ch.extension_number
    WHERE
        ch.start >= (DATE_SUB(DATE(NOW()), INTERVAL 10050 MINUTE))
        AND ch.start <= (DATE(NOW()))
        AND ch.calltype = 'out'
        AND ch.flow = 'out'
        AND ch.extension_number = e.extended_number
    GROUP BY 
       ch.extension_number) AS 'Total Outbound Calls',
    FORMAT(SUM(CAST(ql.arg2 AS UNSIGNED)) / 60, 2) AS 'Total Inbound Duration',
    FORMAT(AVG(CAST(ql.arg2 AS UNSIGNED)) / 60, 2) AS 'Avg Inbound Duration',
    FORMAT(AVG(CAST(ql.arg1 AS UNSIGNED)) / 60, 2) AS 'Avg Caller Hold Time'
FROM
    client c,
    INNER JOIN extension e 
        ON e.client_id = c.id
    INNER JOIN ast_queue_mstatus qs 
        ON qs.membername = e.extended_number
    LEFT JOIN ast_queue_log ql 
        ON ql.queuename = '1234'
        AND ql.`time` >= (DATE_SUB(DATE(NOW()), INTERVAL 7 DAY))
        AND ql.`time` <= (DATE(NOW()))
        AND (
            ql.event = 'COMPLETEAGENT'
            OR ql.event = 'COMPLETECALLER'
            OR ql.event = 'COMPLETETRANSFER')
        AND RIGHT(ql.agent, 8) = qs.membername
GROUP BY ql.agent
ORDER BY c.name;