sql - 用计算表达式更新 sql 临时表列

Question

我执行下面的 SQL 代码。尽管计算表达式不为零，但所有行都更新为零，因为附加信息分母在每种情况下都更大。

UPDATE #t
SET ProportionOfvehicle = (CountOfVehicle / @TotalNumberOfPrivateVehicles)*100
WHERE LegalPersonID IS NOT NULL;

Answer 1

我终于可以自己解决问题了。我创建了一个临时表，其计算字段的数据类型是 float 如下所示

**CREATE TABLE #t
(
    CountOfVehicle BIGINT,
    LegalPersonID BIGINT,
    RegionID BIGINT,
    ProportionOfvehicle FLOAT,
    ProportionOfAccident FLOAT,
    ProportionOfPersonel FLOAT
)**

然后用下面的代码插入除计算字段以外的其他字段

**INSERT  INTO #t
(
    CountOfVehicle,
    LegalPersonID,
    RegionID,
    ProportionOfvehicle,
    ProportionOfAccident,
    ProportionOfPersonel
)
SELECT COUNT(*) AS CountOfVehicle,
       LegalPersonID,
       RegionID,
       NULL AS ProportionOfvehicle,
       NULL AS ProportionOfAccident,
       NULL AS ProportionOfPersonel
FROM Bus.VehicleOwnerships
WHERE OwnershipTypeValue IN (1,2)
GROUP BY LegalPersonID,
         RegionID** 

最后用下面的语句更新计算域

**UPDATE #t
SET ProportionOfvehicle = CountOfVehicle / @TotalNumberOfOrganizationVehicles
WHERE RegionID IS NOT NUL**