sql中sum

㈠ 鍦⊿QL涓錛 sum()鍑芥暟鎬庝箞鐢錛

璇鍙ヤ負錛

withtemp1(col1)as

(select1col1

unionall

selectcol1+1col1

from

temp1

wherecol1+1<=20

)

selectexp(sum(log(col1)))

fromtemp1;

鎵╁睍璧勬枡錛

娉ㄦ剰浜嬮」

sql涓娌℃湁涔樻硶鍑芥暟錛屾墍浠ヤ竴鑸鐢錛

logx+logy=logx*y

瀹炵幇鏂瑰紡錛屽厛瀵硅板綍鍙栧規暟log(),鐒跺悗sum鑱氬悎錛屾渶鍚巈xp錛岀粨鏋滃氨鏄璁板綍鐩鎬箻鐨勭粨鏋溿

SUM鍑芥暟鐨勮娉曟槸錛

SELECT SUM(expression )

FROM tables

WHERE predicates;

琛ㄨ揪寮忓彲浠ユ槸涓涓鏁板煎瓧孌墊垨鍏寮忋

渚嬪傦紝鍙鑳芥兂鐭ラ亾鍚堝苟鍏ㄤ綋鍛樺伐鐨勮柂閲戞婚濈編鍏冧互涓婏紝鍏惰柂閰鏄25,000/騫

SELECT SUM(salary) as "Total Salary"

FROM employees

WHERE salary > 25000;