如何从 ASP.NET Core Web API 应用程序连接到 SQL Server CE 数据库

Question

我已从 ASP.NET 控制台应用程序连接到我的 SQL Server Compact Edition 数据库。我在我的 ASP.NET Core Web API 应用程序中使用相同的东西和库连接到 SQL Server CE 数据库文件，但出现异常。

我的代码：

public  class ClienDetailRepository: IClientDetailRepository
{
    private readonly string _connectionString;

    private static string DbFilePath = @"C:\Git\Forecaster\DB\THSTaxPro.sdf";
    private static string DbPassword = "*****";
    private static string DbMaxSize = "4090";

    public static string ConnectionString = @"Data Source=" + DbFilePath + ";Password=" + DbPassword + ";Max Database Size=" + DbMaxSize + "";

    public ClienDetailRepository(string connectionString)
    {
        _connectionString = connectionString;
        //_connectionString = ConnectionString;
    }
}

我在这条线上遇到错误

  SqlCeConnection sqlconTHS = new SqlCeConnection(ConnectionString);

这是错误：

“System.Data.SqlServerCe.SqlCeConnection”的类型初始值设定项抛出异常

Answer 1

您使用 Windows 吗？我在 Windows 上测试，没有出现你的问题，你可以参考我下面的步骤。

将

System.Data.SqlServerCe.dll

文件和整个

amd64

文件夹从

Microsoft SQL Server Compact Edition\v4.0\Private directory

复制到创建

.csproj

文件的文件夹：

安装 Windows 兼容包，使任何所需的 Windows 特定 .NET API 可用。

在项目的根目录中添加对

System.Data.SqlServerCe.dll

文件的文件引用，您的 .csproj 文件应该像这样结束（我使用的是 .net6）：

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
    <RootNamespace>ProjectName</RootNamespace>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Windows.Compatibility" Version="6.0.3" />
  </ItemGroup>

    <ItemGroup>
        <None Remove="amd64\Microsoft.VC90.CRT\Microsoft.VC90.CRT.manifest" />
        <None Remove="amd64\Microsoft.VC90.CRT\msvcr90.dll" />
        <None Remove="amd64\Microsoft.VC90.CRT\README_ENU.txt" />
        <None Remove="amd64\sqlceca40.dll" />
        <None Remove="amd64\sqlcecompact40.dll" />
        <None Remove="amd64\sqlceer40EN.dll" />
        <None Remove="amd64\sqlceme40.dll" />
        <None Remove="amd64\sqlceqp40.dll" />
        <None Remove="amd64\sqlcese40.dll" />
        <None Remove="System.Data.SqlServerCe.dll" />
    </ItemGroup>

    <ItemGroup>
        <Content Include="amd64\Microsoft.VC90.CRT\Microsoft.VC90.CRT.manifest">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\Microsoft.VC90.CRT\msvcr90.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\Microsoft.VC90.CRT\README_ENU.txt">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\sqlceca40.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\sqlcecompact40.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\sqlceer40EN.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\sqlceme40.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\sqlceqp40.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="amd64\sqlcese40.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
        <Content Include="System.Data.SqlServerCe.dll">
            <CopyToOutputDirectory>Always</CopyToOutputDirectory>
        </Content>
    </ItemGroup>

    <ItemGroup>
        <Reference Include="System.Data.SqlServerCe, Version=4.0.0.1">
            <HintPath>System.Data.SqlServerCe.dll</HintPath>
        </Reference>
    </ItemGroup>

我的测试代码：

string connectionString = "Data Source=THSTaxPro.sdf";

//using SqlCeEngine engine = new SqlCeEngine(connectionString);
//engine.CreateDatabase();

using SqlCeConnection connection = new SqlCeConnection(connectionString);
connection.Open();

using (SqlCeCommand command = connection.CreateCommand())
{
    //command.CommandText = "CREATE TABLE Blogs ( Id INT, Title NVARCHAR(256) )";

    //command.ExecuteNonQuery();

    command.CommandText = "SELECT * FROM Blogs";

    SqlCeDataReader reader = command.ExecuteReader();

    int Count = reader.FieldCount;
}

当然，请确保你的connectionString是正确的。

测试结果：

更多详情，您可以参考此链接。