DataTable与一个byte []字段作为存储过程的参数 [英] DataTable with a byte[] field as parameter to a stored procedure
问题描述
我一直在重用这种使用DataTable作为存储过程的参数的方法,并且一直在很好。这是简化的工作代码:
I've been reusing this method of using a DataTable as a parameter to a stored procedure and it's been working great. This is the simplified working code:
using (dbEntities dbe = new dbEntities())
{
var dt = new dataTable();
dt.Columns.Add("ID");
dt.Columns.Add("Message");
dt.Columns.Add("CreatedOn", typeof(DateTime));
foreach (var row in randomDataSource)
{
dt.Rows.Add(
row.id,
row.message,
DateTime.Now
);
}
var tableType = new SqlParameter("tableType", SqlDbType.Structured);
tableType.Value = dt;
tableType.TypeName = "[dbo].[RandomTableType]";
dbe.ExecuteStoreCommand(
"EXEC [dbo].[SaveTable] @tableType",
new object[] { tableType }
);
}
当我要添加的字段是二进制类型时,出现问题。即:
The problem arises when the field I want to add is of a binary type. i.e.:
dt.Columns.Add("BinaryMessage", typeof(byte[]));
数据库中的相应列是 varbinary(MAX)
顺便一提。当我尝试运行它,我得到这个错误:
The corresponding column in the database is varbinary(MAX)
by the way. When I try to run this, I get this error:
从数据类型nvarchar(max)到varbinary(max)的隐式转换是
不允许。使用CONVERT函数来运行这个查询。
Implicit conversion from data type nvarchar(max) to varbinary(max) is not allowed. Use the CONVERT function to run this query.
如何修改我要做的工作? $ b
How do I modify what I have to make this work?
推荐答案
.NET中的二进制字符串的表示是 SqlBinary
结构。
The representation for a binary string in .NET is the SqlBinary
structure.
你想添加这样的列:
dt.Columns.Add("BinaryMessage", typeof(SqlBinary));
SqlBinary
类有一个显式转换为字节数组和从字节数组的隐式转换,所以从字节数组到列的值是一个简单的分配问题,而从列中获取字节数组需要显式转换。
The SqlBinary
class has an explicit conversion to a byte array and an implicit conversion from a byte array, so the value from a byte array to the column is a simple matter of assignment, while getting a byte array from the column requires an explicit cast.
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