根据值更新多行，使用 C# DBContext 和本机查询

Question

public class Selecter
{
    public string SelecterId { get; set; }
    public string UniqueText { get; set; } 
    public string OutputError { get; set; }
    public bool Selected { get; set; }
}

modelBuilder.Entity("WebAssistantClient.Models.Selecter", b =>
    {
        b.Property<string>("SelecterId").HasColumnType("nvarchar(450)");
        b.Property<string>("OutputError").HasColumnType("nvarchar(max)");
        b.Property<bool>("Selected").HasColumnType("bit");
        b.Property<string>("UniqueText").HasColumnType("nvarchar(max)");
        b.HasKey("TestSelecterId");
        b.ToTable("TestSelecters");
    }
);

CREATE TABLE [dbo].[Selecters](
    [SelecterId] [nvarchar](450) NOT NULL,
    [UniqueText] [nvarchar](max) NULL,
    [OutputError] [nvarchar](max) NULL,
    [Selected] [bit](max) NULL,
    CONSTRAINT [PK_Selecters] PRIMARY KEY CLUSTERED ([SelecterId] ASC)
)

假设这是我的初始数据：

SelecterId  UniqueText  Selected
"fruit0"    "apple"     false
"fruit1"    "banana"    true
"fruit2"    "lemon"     false
"fruit3"    ""          false

要求 1

当我将某些行的 Selected 列设置为 true，但将其他行的 Selected 列更改为 false 时，我需要：示例：对于“fruit0”选择为 true，其列中的其他行 Selected 将为 false，在本例中为“fruit1”

SelecterId  UniqueText  Selected
"fruit0"    "apple"     true
"fruit1"    "banana"    false
"fruit2"    "lemon"     false
"fruit3"    ""          false

要求 2

我需要将 UniqueText 列设置为某行的值，但如果包含相同的值，则将另一行 UniqueText 列更改为“”（空）：示例：对于“fruit3”UniqueText 为“lemon”，具有相同值的另一行变为空“”，在本例中为“fruit2”

SelecterId  UniqueText  Selected
"fruit0"    "apple"     true
"fruit1"    "banana"    false
"fruit2"    ""          false
"fruit3"    "lemon"     false

使用SQL服务器，是否可以一句话完成要求？

使用 C#，如何使用 context.Selecter.FromSqlRaw("???");

Answer 1

Using SQL Server, Is it possible to do the requirements in one single sentence?

您 select both/all 您感兴趣的，然后使用条件集来计算要应用的值

Example: for "fruit0" Selected to true, the other rows in their colum Selected will be false, in this case the "fruit1"

UPDATE fruits 
SET Selected = CASE WHEN SelecterId = 'fruit0' THEN 'true' ELSE 'false' END 
WHERE selecterId = 'fruit0' OR Selected = 'true'

for "fruit3" UniqueText to "lemon", the another row with same value become to empty "", in this case the "fruit2"

UPDATE fruits 
SET UniqueText = CASE WHEN SelecterId = 'fruit3' THEN 'lemon' ELSE '' END 
WHERE SelecterId = 'fruit3' OR UniqeText = 'lemon'

作为一般模式：

UPDATE table
SET column_to_change = CASE WHEN identifying_column = 'id_value_you_know' ELSE 'resting_value' END
WHERE identifying_column = 'id_value_you_know' OR column_to_change = 'resting_value'

您应该始终知道您更改的列、您标识某些记录的列、您标识的值以及您更改的列的剩余值

根据值更新多行，使用 C# DBContext 和本机查询

Updating Multiple Rows, Depending on Value, Using C# DBContext, and native Query

c#

sql-server

sql-update

dbcontext