有人可以告訴我如何使用加快這個MySQL查詢。我知道它由於計數(distinct subcontractorRef)語法而正在運行緩慢。任何其他的選擇?我怎麼能加快MySQL查詢時使用運行一個選擇使用計數(清晰)查詢
SELECT DISTINCT (contractorsRef) AS cref, RIDGROUP AS ridg,
(select count(DISTINCT subcontractorRef)
FROM request
INNER JOIN request_config ON request_config.RIDGROUP = request.RIDGROUP
WHERE request_config.contractorsRef = outer_config.contractorsRef
AND currenttaxyear =2011
AND weekno =31) AS xxx
FROM request_config outer_config
WHERE currenttaxyear =2011
AND weekno =32
AND contractorsRef <>132
請將'EXPLAIN SELECT ...','SHOW CREATE TABLE request_config'和'SHOW CREATE TABLE request'的輸出貼出來。 –
首先回答所有數據庫加速問題:索引。你有嘗試過嗎? –