sql中sum

㈠ 鍦⊿QL涓锛 sum()鍑芥暟镐庝箞鐢锛

璇鍙ヤ负锛

withtemp1(col1)as

(select1col1

unionall

selectcol1+1col1

from

temp1

wherecol1+1<=20

)

selectexp(sum(log(col1)))

fromtemp1;

镓╁𪾢璧勬枡锛

娉ㄦ剰浜嬮”

sql涓娌℃湁涔樻硶鍑芥暟锛屾墍浠ヤ竴鑸鐢锛

logx+logy=logx*y

瀹炵幇鏂瑰纺锛屽厛瀵硅板綍鍙栧规暟log(),铹跺悗sum镵氩悎锛屾渶钖巈xp锛岀粨鏋滃氨鏄璁板綍鐩镐箻镄勭粨鏋溿

SUM鍑芥暟镄勮娉曟槸锛

SELECT SUM(expression )

FROM tables

WHERE predicates;

琛ㄨ揪寮忓彲浠ユ槸涓涓鏁板煎瓧娈垫垨鍏寮忋

渚嫔傦纴鍙鑳芥兂鐭ラ亾钖埚苟鍏ㄤ綋锻桦伐镄勮柂閲戞婚濈编鍏冧互涓婏纴鍏惰柂閰鏄25,000/骞

SELECT SUM(salary) as "Total Salary"

FROM employees

WHERE salary > 25000;