相关疑难解决方法(0)

为什么 NOT NULL 计算列在视图中被认为可以为空?

我有一张桌子:

CREATE TABLE [dbo].[Realty](
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [RankingBonus] [int] NOT NULL,
    [Ranking]  AS ([Id]+[RankingBonus]) PERSISTED NOT NULL
    ....
)
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还有一个观点:

CREATE View  [dbo].[FilteredRealty] AS
 SELECT 
realty.Id as realtyId,
...
COALESCE(realty.Wgs84X, ruian_cobce.Wgs84X, ruian_obec.Wgs84X) as Wgs84X,
COALESCE(realty.Wgs84Y, ruian_cobce.Wgs84Y, ruian_obec.Wgs84Y) as Wgs84Y,
realty.Ranking,
...
FROM realty
JOIN Category ON realty.CategoryId = Category.Id
LEFT JOIN ruian_cobce ON realty.cobceId = ruian_cobce.cobce_kod
LEFT JOIN ruian_obec ON realty.obecId = ruian_obec.obec_kod
LEFT JOIN okres ON realty.okresId = okres.okres_kod
LEFT JOIN ExternFile ON realty.Id = ExternFile.ForeignId AND …
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null sql-server view computed-column

17
推荐指数
2
解决办法
8741
查看次数

未使用计算列索引

我想根据两列是否相等进行快速查找。我尝试使用带有索引的计算列,但 SQL Server 似乎没有使用它。如果我只使用带有索引的静态填充位列,我会得到预期的索引查找。

似乎还有其他一些类似的问题,但没有一个关注为什么不使用索引。

测试表:

CREATE TABLE dbo.Diffs
    (
    Id int NOT NULL IDENTITY (1, 1),
    DataA int NULL,
    DataB int NULL,
    DiffPersisted  AS isnull(convert(bit, case when [DataA] is null and [DataB] is not null then 1 when [DataA] <> [DataB] then 1 else 0 end), 0) PERSISTED ,
    DiffComp  AS isnull(convert(bit, case when [DataA] is null and [DataB] is not null then 1 when [DataA] <> [DataB] then 1 else 0 end), 0),
    DiffStatic bit not null,
    Primary …
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sql-server index-tuning computed-column

14
推荐指数
2
解决办法
1085
查看次数

标签 统计

computed-column ×2

sql-server ×2

index-tuning ×1

null ×1

view ×1