try
UPDATE T
SET T.[cgsl] = sum(S.[cgsl])
FROM [sbgl] T
INNER JOIN (SELECT isnull(a.dw,b.dw) as dw,isnull(a.sbdm,b.sbdm) as sbdm,(isnull(sum(a.xysl),0)+ isnull(sum(b.xysl),0) as ) cgsl
FROM [sbcgjl] a
INNER JOIN [sbsyjl] b ON a.dw=b.dw and a.sbdm=b.sbdm
GROUP BY isnull(a.dw,b.dw),isnull(a.sbdm,b.sbdm)
)
S ON S.dw=T.dw and S.sbdm=T.sbdm
UPDATE T
SET T.[cgsl] = sum(S.[cgsl])
FROM [sbgl] T
INNER JOIN (SELECT isnull(a.dw,b.dw) as dw,isnull(a.sbdm,b.sbdm) as sbdm,(isnull(sum(a.xysl),0)+ isnull(sum(b.xysl),0) as ) cgsl
FROM [sbcgjl] a
INNER JOIN [sbsyjl] b ON a.dw=b.dw and a.sbdm=b.sbdm
GROUP BY isnull(a.dw,b.dw),isnull(a.sbdm,b.sbdm)
)
S ON S.dw=T.dw and S.sbdm=T.sbdm
UPDATE T
SET T.[cgsl] = sum(S.[cgsl])
FROM [sbgl] T
INNER JOIN (SELECT isnull(a.dw,b.dw) as dw,isnull(a.sbdm,b.sbdm) as sbdm,(isnull(sum(a.xysl),0)+ isnull(sum(b.xysl),0) as ) cgsl
FROM [sbcgjl] a
LEFT JOIN [sbsyjl] b ON a.dw=b.dw and a.sbdm=b.sbdm --INNER JOIN换成LEFT JOIN
GROUP BY isnull(a.dw,b.dw),isnull(a.sbdm,b.sbdm)
)
S ON S.dw=T.dw and S.sbdm=T.sbdm