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此更新語句太慢更新表中選擇多個表
UPDATE planner_ccy a
SET dxy = (SELECT b.close FROM dxy b WHERE b.trade_date <= a.trade_date ORDER BY b.trade_date DESC LIMIT 1),
usd_rate = (SELECT c.interest_rate FROM usd_ir c WHERE c.set_date <= a.trade_date ORDER BY c.set_date DESC LIMIT 1),
ccy_rate = (SELECT d.interest_rate FROM ccy_ir d WHERE d.set_date <= a.trade_date ORDER BY d.set_date DESC LIMIT 1),
coal = (SELECT e.price FROM coal e WHERE e.reported_date <= a.trade_date ORDER BY e.reported_date DESC LIMIT 1),
oil = (SELECT f.price FROM oil f WHERE f.reported_date <= a.trade_date ORDER BY f.reported_date DESC LIMIT 1),
ump = (SELECT g.ump_rate FROM usd_ur g WHERE g.reported_month <= a.trade_date ORDER BY g.reported_month DESC LIMIT 1),
inx = (SELECT h.close FROM inx h WHERE h.trade_date <= a.trade_date ORDER BY h.trade_date DESC LIMIT 1)/(SELECT i.gdp FROM fed_ i WHERE i.reported_year <= a.trade_date ORDER BY i.reported_year DESC LIMIT 1),
total = (SELECT j.total FROM fed_ j WHERE j.reported_year <= a.trade_date ORDER BY j.reported_year DESC LIMIT 1)/(SELECT k.gdp FROM fed_ k WHERE k.reported_year <= a.trade_date ORDER BY k.reported_year DESC LIMIT 1),
dfn = (SELECT n.dfn FROM fed_ n WHERE n.reported_year <= a.trade_date ORDER BY n.reported_year DESC LIMIT 1)/(SELECT o.gdp FROM fed_ o WHERE o.reported_year <= a.trade_date ORDER BY o.reported_year DESC LIMIT 1),
tax = (SELECT p.tax_rate*p.tax_bracket FROM usd_tax p WHERE p.set_date <= a.trade_date ORDER BY p.set_date DESC LIMIT 1)/(SELECT q.gdp FROM fed_ q WHERE q.reported_year <= a.trade_date ORDER BY q.reported_year DESC LIMIT 1)/1000000000,
forecast = (SELECT r.close FROM ccyusd r WHERE r.trade_date <= a.trade_date ORDER BY r.trade_date DESC LIMIT MasterSkip,1)
WHERE a.trade_date >= Start;
當我嘗試使用下面的左邊加入，只有幾行得到更新。我怎樣才能使用左連接？
UPDATE planner_ccy_ a
LEFT JOIN (SELECT * FROM dxy ORDER BY trade_date DESC LIMIT 1) AS b
ON b.trade_date <= a.trade_date
LEFT JOIN (SELECT * FROM usd_ir ORDER BY set_date DESC LIMIT 1) AS c
ON c.set_date <= a.trade_date
LEFT JOIN (SELECT * FROM ccy_ir ORDER BY set_date DESC LIMIT 1) AS d
ON d.set_date <= a.trade_date
LEFT JOIN (SELECT * FROM coal ORDER BY reported_date DESC LIMIT 1) AS e
ON e.reported_date <= a.trade_date
LEFT JOIN (SELECT * FROM oil ORDER BY reported_date DESC LIMIT 1) AS f
ON f.reported_date <= a.trade_date
LEFT JOIN (SELECT * FROM usd_ur ORDER BY reported_month DESC LIMIT 1) AS g
ON g.reported_month <= a.trade_date
LEFT JOIN (SELECT * FROM inx ORDER BY trade_date DESC LIMIT 1) AS h
ON h.trade_date <= a.trade_date
LEFT JOIN (SELECT * FROM fed_ ORDER BY reported_year DESC LIMIT 1) AS i
ON i.reported_year <= a.trade_date
LEFT JOIN (SELECT * FROM usd_tax ORDER BY set_date DESC LIMIT 1) AS j
ON j.set_date <= a.trade_date
LEFT JOIN (SELECT * FROM ccyusd ORDER BY trade_date DESC LIMIT MasterSkip,1) AS k
ON K.trade_date <= a.trade_date
SET a.dxy = b.close,
a.usd_rate = c.interest_rate,
a.ccy_rate = d.interest_rate,
a.coal = e.price,
a.oil = f.price,
a.ump = g.ump_rate,
a.inx = h.close /i.gdp,
a.total = i.total/i.gdp,
a.dfn = i.dfn/i.gdp,
a.tax = j.tax_rate*j.tax_bracket/i.gdp/1000000000,
a.forecast = K.close
WHERE a.trade_date >= Start;
我需要通過從多個表中選擇值來更新單個表。現在，第一個選項太慢，可以正確執行，但效率不高。我一直在閱讀，認爲連接更有效率，實際上這個查詢是從我以前的遊標遷移過來並且速度太慢。