“值不能为null.\\参数名称：providerinvariantname”，在C＃窗体中，错误dbprovider factorie（dataprovider name）not null如何修复这些 [英] "Value cannot be null.\r\nparameter name: providerinvariantname"}, in C# windows form, error dbprovider factorie (dataprovider name) not null how fix these

问题描述

  public   static  DbCommand CreateCommand（）
 { 
  //   WebConfigReader  
  / /  获取数据库提供者名称 
  string  dataProviderName = WebConfigReader.DbProviderName; 
  //  获取数据库连接字符串 
  string  connectionString = WebConfigReader.DbConnectionString; 
  //  创建新的数据提供者工厂 
 DbProviderFactory factory = DbProviderFactories.GetFactory （dataProviderName）; 
  //  获取数据库特定的连接对象 
 DbConnection conn = factory.CreateConnection （）; 
  //  设置连接字符串 
 conn.ConnectionString = connectionString; 
  //  创建特定于数据库的命令对象 
 DbCommand comm = conn.CreateCommand （）; 
  //  将命令类型设置为存储过程 
 comm.CommandType = CommandType .StoredProcedure; 
  //  返回初始化的命令对象 
 返回 comm; 
} 
} 
} 

我尝试了什么：



i尝试更改dbprovider名称和连接字符串如何修复

解决方案

查看错误消息：

值不能为空。 
参数名称：providerinvariantname 

这是来自您的数据库，意味着您尝试在声明为的列上插入或更新具有空值的列NOT NULL。



我们无法解决这个问题：这是你的数据库，还有你的数据！允许空值 - 在这种情况下更改您的数据库 - 或者它们不是 - 在这种情况下清理您的数据输入。

我们不能为您执行任何操作...

错误消息表明 WebConfigReader.DbProviderName 正在返回 null 。您需要调试代码以找出原因。

public static DbCommand CreateCommand()
{ 
            //WebConfigReader 
            // Obtain the database provider name
            string dataProviderName = WebConfigReader.DbProviderName;
            // Obtain the database connection string
            string connectionString = WebConfigReader.DbConnectionString;
            // Create a new data provider factory
            DbProviderFactory factory = DbProviderFactories.GetFactory(dataProviderName);
            // Obtain a database specific connection object
            DbConnection conn = factory.CreateConnection();
            // Set the connection string
            conn.ConnectionString = connectionString;
            // Create a database specific command object
            DbCommand comm = conn.CreateCommand();
            // Set the command type to stored procedure
            comm.CommandType = CommandType.StoredProcedure;
            // Return the initialized command object
            return comm;
        }
    }
}

What I have tried:

i tried to change dbprovider name and connection string how to fix

解决方案

Look at the error message:

Value cannot be null.
parameter name: providerinvariantname

That is coming from your DB and means that you are trying to insert or update a column with a null value on a column declared as NOT NULL.

We can't fix that: it's your DB, and your data! Either nulls are allowed - in which case change your DB - or they aren't - in which case sanitize your data inputs.
We can't do any of that for you...

The error message would suggest that WebConfigReader.DbProviderName is returning null. You'll need to debug your code to find out why.

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