我编写了一个查询，其中包含多个连接和 sum（if（））条件。 我正在使用 MySql 数据库。 查询结构如下所示： *查询从多个表连接（准确地说是7），总和（if（））条件表示美国的总共53个状态。*查询执行几乎 20分钟是一个很长的时期。
如果有人可以建议我如何减少这么长的时间。
SELECT ag.position_id AS 'position_id',
ag.npn AS 'NPN',
concat(ag.first_name, ' ', ag.last_name) AS 'full_name',
lb.name AS 'lob',
location_lic AS 'loc',
COUNT(DISTINCT lt.id) AS 'RTS_Total',
SUM(IF(st.id = 1, 1, 0)) AS 'AK',
SUM(IF(st.id = 2, 1, 0)) AS 'AL',
SUM(IF(st.id = 3, 1, 0)) AS 'AR',
SUM(IF(st.id = 4, 1, 0)) AS 'AZ',
SUM(IF(st.id = 5, 1, 0)) AS 'CA',
SUM(IF(st.id = 6, 1, 0)) AS 'CO',
SUM(IF(st.id = 7, 1, 0)) AS 'CT',
SUM(IF(st.id = 8, 1, 0)) AS 'DC',
SUM(IF(st.id = 9, 1, 0)) AS 'DE',
SUM(IF(st.id = 10, 1, 0)) AS 'FL',
SUM(IF(st.id = 11, 1, 0)) AS 'GA',
SUM(IF(st.id = 12, 1, 0)) AS 'HI',
SUM(IF(st.id = 13, 1, 0)) AS 'IA',
SUM(IF(st.id = 14, 1, 0)) AS 'ID',
SUM(IF(st.id = 15, 1, 0)) AS 'IL',
SUM(IF(st.id = 16, 1, 0)) AS 'IN',
SUM(IF(st.id = 17, 1, 0)) AS 'KS',
SUM(IF(st.id = 18, 1, 0)) AS 'KY',
SUM(IF(st.id = 19, 1, 0)) AS 'LA',
SUM(IF(st.id = 20, 1, 0)) AS 'MA',
SUM(IF(st.id = 21, 1, 0)) AS 'MD',
SUM(IF(st.id = 22, 1, 0)) AS 'ME',
SUM(IF(st.id = 23, 1, 0)) AS 'MI',
SUM(IF(st.id = 24, 1, 0)) AS 'MN',
SUM(IF(st.id = 25, 1, 0)) AS 'MO',
SUM(IF(st.id = 26, 1, 0)) AS 'MS',
SUM(IF(st.id = 27, 1, 0)) AS 'MT',
SUM(IF(st.id = 28, 1, 0)) AS 'NC',
SUM(IF(st.id = 29, 1, 0)) AS 'ND',
SUM(IF(st.id = 30, 1, 0)) AS 'NE',
SUM(IF(st.id = 31, 1, 0)) AS 'NH',
SUM(IF(st.id = 32, 1, 0)) AS 'NJ',
SUM(IF(st.id = 33, 1, 0)) AS 'NM',
SUM(IF(st.id = 34, 1, 0)) AS 'NV',
SUM(IF(st.id = 35, 1, 0)) AS 'NY',
SUM(IF(st.id = 36, 1, 0)) AS 'OH',
SUM(IF(st.id = 37, 1, 0)) AS 'OK',
SUM(IF(st.id = 38, 1, 0)) AS 'OR',
SUM(IF(st.id = 39, 1, 0)) AS 'PA',
SUM(IF(st.id = 40, 1, 0)) AS 'PR',
SUM(IF(st.id = 41, 1, 0)) AS 'RI',
SUM(IF(st.id = 42, 1, 0)) AS 'SC',
SUM(IF(st.id = 43, 1, 0)) AS 'SD',
SUM(IF(st.id = 44, 1, 0)) AS 'TN',
SUM(IF(st.id = 45, 1, 0)) AS 'TX',
SUM(IF(st.id = 46, 1, 0)) AS 'UT',
SUM(IF(st.id = 47, 1, 0)) AS 'VA',
SUM(IF(st.id = 48, 1, 0)) AS 'VI',
SUM(IF(st.id = 49, 1, 0)) AS 'VT',
SUM(IF(st.id = 50, 1, 0)) AS 'WA',
SUM(IF(st.id = 51, 1, 0)) AS 'WI',
SUM(IF(st.id = 52, 1, 0)) AS 'WV',
SUM(IF(st.id = 53, 1, 0)) AS 'WY'
FROM cxprtsapp_licensetracker lt
INNER JOIN cxprtsapp_agents ag ON ag.id = lt.agent_id_id AND ag.position_status LIKE 'Active'
LEFT JOIN cxprtsapp_statelobjit slj ON slj.state_id = lt.state_id_id AND ag.lob_id = slj.lob_id
LEFT JOIN
(select npn, rtsreport_appointed, rtsreport_licensed, state_id, lob_id
from cxprtsapp_rtslob
order BY refresh_number desc
) rts ON rts.state_id = lt.state_id_id and ag.lob_id = rts.lob_id and ag.npn=rts.npn
INNER JOIN cxprtsapp_location lc ON lc.id = ag.loc_id
INNER JOIN cxprtsapp_lineofbussiness lb ON lb.id = ag.lob_id
INNER JOIN cxprtsapp_states st ON st.id = lt.state_id_id
LEFT JOIN
(SELECT DISTINCT npn, state_code, status
FROM cxprtsapp_pdbappointments
WHERE status LIKE 'Appointed'
) appt ON appt.npn = ag.npn AND appt.state_code = st.state_code
WHERE certification_id IS NOT NULL
AND (expiration_date IS NULL OR expiration_date > CURDATE())
AND (slj.jit = 1 OR rts.rtsreport_appointed = 1 OR appt.status IS NOT NULL)
GROUP BY ag.id, ag.lob_id,loc_id ORDER BY ag.hire_date DESC;
解决方案：
查询所需的时间从10-15分钟减少到10-20秒。
我们必须改变数据库索引的性能。
我们必须首先在数据库中运行下面的sql查询。
ALTER TABLE cxprtsapp_agents ADD INDEX cxprtsapp_agents_idx_status_id_id_npn_id (position_status,id,lob_id,npn,loc_id);
ALTER TABLE cxprtsapp_licensetracker ADD INDEX cxprtsapp_licensetra_idx_id_id_id_id (agent_id_id,state_id_id,certification_id,id);
ALTER TABLE cxprtsapp_lineofbussiness ADD INDEX cxprtsapp_lineofbuss_idx_id_name (id,name);
ALTER TABLE cxprtsapp_location ADD INDEX cxprtsapp_location_idx_id_lic (id,location_lic);
ALTER TABLE cxprtsapp_statelobjit ADD INDEX cxprtsapp_statelobji_idx_id_id (state_id,lob_id);
ALTER TABLE cxprtsapp_states ADD INDEX cxprtsapp_states_idx_id_code (id,state_code);
ALTER TABLE cxprtsapp_rtslob ADD INDEX cxprtsapp_rtslob_idx_numbe_npn_appoi_licen_id_id (refresh_number,npn,rtsreport_appointed,rtsreport_licensed,state_id,lob_id);
ALTER TABLE cxprtsapp_pdbappointments ADD INDEX cxprtsapp_pdbappoint_idx_status_npn_code (status,npn,state_code);