c# – IDbCommand MySQL和SQL Server的命名参数

我一直在尝试创建一些DB独立代码,如下所示：

IDbCommand command = connection.CreateCommand();
command.CommandText = "...";

IDbDataParameter param1 = command.CreateParameter();
param1.ParameterName = "param1";
param1.Value = "value";
command.Parameters.Add(param1);

适用于MysqL的命令文本是：

select * from mytable where field1 = ?param1

适用于sqlserver的命令文本是：

select * from mytable where field1 = @param1

是否有某种形式适用于两者？

编辑：

> sql Server 2008R2
> MysqL 5.0.X

解决方法

不,我认为没有这样的方法.所以你必须提供自己的：

public static String GetProviderParameter(string paramName,IDbConnection con)
{
    string prefix = "";
    if(con is System.Data.sqlClient.sqlConnection)
        prefix = "@";
    else if(con is System.Data.OleDb.OleDbConnection)
        prefix =  "?";
    else if(con is System.Data.Odbc.OdbcConnection)
        prefix =  "?";
    else if(con is MysqL.Data.MysqLClient.MysqLConnection)
        prefix =  "?";

    return prefix + paramName;
}

用法：

param1.ParameterName = GetProviderParameter("param1",connection);

或者您可以使用this扩展,它使用反射来使用DbCommandBuilder类中的受保护方法GetParameterName：

public static class Db
{
    static readonly Func<DbConnection,DbProviderFactory> getDbProviderFactory = 
        (Func<DbConnection,DbProviderFactory>)Delegate.CreateDelegate(typeof(Func<DbConnection,DbProviderFactory>),typeof(DbConnection).GetProperty("DbProviderFactory",BindingFlags.Instance | BindingFlags.NonPublic).Getgetmethod(true));
    static readonly Func<DbCommandBuilder,string,string> getParameterName =
        (Func<DbCommandBuilder,string>)Delegate.CreateDelegate(typeof(Func<DbCommandBuilder,string>),typeof(DbCommandBuilder).getmethod("GetParameterName",BindingFlags.Instance | BindingFlags.NonPublic,Type.DefaultBinder,new Type[] { typeof(string) },null));

    public static DbProviderFactory GetProviderFactory(this DbConnection connection)
    {
        return getDbProviderFactory(connection);
    }

    public static string GetParameterName(this DbConnection connection,string paramName)
    {
        DbCommandBuilder builder = GetProviderFactory(connection).CreateCommandBuilder();

        return getParameterName(builder,paramName);
    }
}

然后它很简单：

param1.ParameterName = connection.GetParameterName("param1");