sql中保留到小数点后两位以及非空判断赋值为零

SELECT a.dzzmc, a.dzzdm, a.px, CONVERT(decimal(18, 2), ISNULL(b.sjpfzdf, 0) * 0.6 + (ISNULL(a.zddfzdf, 0) + ISNULL(b.zddfzdf, 0)) / 2 * 0.4) AS zzdf, CONVERT(decimal(18, SELECT a.dzzmc, a.dzzdm, a.px, CONVERT(decimal(