Mysql o在不了解表格结构的情况下提供帮助。但是，WHERE子句限制了要分析的行数，而如果WHERE子句不存在，则将执行完整的表扫描，因此您的结果是预期的。我可以建议的是将查询剥离到最小值，然后逐个添加连接，直到您开始看到查询性能的显著提升，然后再进行处理。此外，

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o在不了解表格结构的情况下提供帮助。但是，WHERE子句限制了要分析的行数，而如果WHERE子句不存在，则将执行完整的表扫描，因此您的结果是预期的。我可以建议的是将查询剥离到最小值，然后逐个添加连接，直到您开始看到查询性能的显著提升，然后再进行处理。此外，嵌套的select FROM LK_标记LT是一个瓶颈，因为它将针对每个元组运行，这意味着如果您正在进行完整的表扫描（即，无WHERE子句），那么它将针对每一行运行。在

M_CLIENT_INFO

表中有多少行？您可能会生成太多的结果，以至于数据库或MySQL工作台的链接都饱和了。请张贴你的执行计划。请尝试从CLI进行查询。@crafter:谢谢，我会回来做更多解释。@RandomSeed如果您将where子句更改为

where YEAR（MCI.DATE\u ADDED）不为NULL，它将在合理的时间内提供输出吗？
 SELECT 
        MCI.CLIENT_ID AS CLIENT_ID, MCI.NAME AS CLIENT_NAME, MCI.PRIMARY_CONTACT AS CLIENT_PRIMARY_CONTACT, 
        MCI.ADDED_BY AS SP_ID, CONCAT(MUD_SP.FIRST_NAME, ' ', MUD_SP.LAST_NAME) AS SP_NAME, 
        MCI.FK_PROSPECT_ID AS PROSPECT_ID, MCI.DATE_ADDED AS ADDED_ON,
        (SELECT GROUP_CONCAT(LT.TAG_TEXT SEPARATOR ', ') 
            FROM LK_TAG LT
            INNER JOIN M_OBJECT_TAG_MAPPING MOTM
            ON LT.PK_ID = MOTM.FK_TAG_ID
            WHERE MOTM.FK_OBJECT_ID = MCI.FK_PROSPECT_ID
                AND MOTM.OBJECT_TYPE = 1
                AND MOTM.IS_ACTIVE = 1
        ) AS TAGS,
        IFNULL(SUM(GET_DIGITS(MMR.RCP_AMOUNT)), 0) AS REVENUE_SO_FAR,
        IFNULL(SUM(GET_DIGITS(MMR.RCP_RUPEES)), 0) AS REVENUE_INR,
        COUNT(DISTINCT PMI_MONTHLY.PROJECT_ID) AS MONTHLY,
        COUNT(DISTINCT PMI_FIXED.PROJECT_ID) AS FIXED,
        COUNT(DISTINCT PMI_HOURLY.PROJECT_ID) AS HOURLY,
        COUNT(DISTINCT PMI_ANNUAL.PROJECT_ID) AS ANNUAL,
        COUNT(DISTINCT PMI_CURRENTLY_RUNNING.PROJECT_ID) AS CURRENTLY_RUNNING_PROJECTS,
        COUNT(DISTINCT PMI_YET_TO_START.PROJECT_ID) AS YET_TO_START_PROJECTS,
        COUNT(DISTINCT PMI_TECH_SALES_CLOSED.PROJECT_ID) AS TECH_SALES_CLOSED_PROJECTS
    FROM 
        M_CLIENT_INFO MCI
        INNER JOIN M_USER_DETAILS MUD_SP
            ON MCI.ADDED_BY = MUD_SP.PK_ID
        LEFT OUTER JOIN M_MONTH_RECEIPT MMR
                ON MMR.CLIENT_ID = MCI.CLIENT_ID
        LEFT OUTER JOIN M_PROJECT_INFO PMI_FIXED
                ON PMI_FIXED.CLIENT_ID =  MCI.CLIENT_ID AND PMI_FIXED.PROJECT_TYPE = 1
        LEFT OUTER JOIN M_PROJECT_INFO PMI_MONTHLY
                ON PMI_MONTHLY.CLIENT_ID =  MCI.CLIENT_ID AND PMI_MONTHLY.PROJECT_TYPE = 2
        LEFT OUTER JOIN M_PROJECT_INFO PMI_HOURLY
                ON PMI_HOURLY.CLIENT_ID =  MCI.CLIENT_ID AND PMI_HOURLY.PROJECT_TYPE = 3
        LEFT OUTER JOIN M_PROJECT_INFO PMI_ANNUAL
                ON PMI_ANNUAL.CLIENT_ID =  MCI.CLIENT_ID AND PMI_ANNUAL.PROJECT_TYPE = 4
        LEFT OUTER JOIN M_PROJECT_INFO PMI_CURRENTLY_RUNNING
                ON PMI_CURRENTLY_RUNNING.CLIENT_ID =  MCI.CLIENT_ID AND PMI_CURRENTLY_RUNNING.STATUS = 4
        LEFT OUTER JOIN M_PROJECT_INFO PMI_YET_TO_START
                ON PMI_YET_TO_START.CLIENT_ID =  MCI.CLIENT_ID AND PMI_YET_TO_START.STATUS < 4
        LEFT OUTER JOIN M_PROJECT_INFO PMI_TECH_SALES_CLOSED
                ON PMI_TECH_SALES_CLOSED.CLIENT_ID =  MCI.CLIENT_ID AND PMI_TECH_SALES_CLOSED.STATUS > 4
               WHERE YEAR(MCI.DATE_ADDED) = '2012'
                GROUP BY MCI.CLIENT_ID ORDER BY CLIENT_NAME ASC  

where 1 = 1

select
      PQ.*,
      group_concat(...) tags
   from
      ( the entire primary part of the query ) as PQ
         Left join yourGroupConcatTableBasis on key columns