从文件中插入图像
可以将二进制大型对象 (BLOB) 作为二进制数据或字符数据（具体视数据源中的字段类型而定）写入数据库。 BLOB 这一通用术语是指，通常包含文档和图片的 text、ntext 和 image 数据类型。
若要将 BLOB 值写入数据库，请发出相应的 INSERT 或 UPDATE 语句并将 BLOB 值作为输入参数传递（请参见配置参数和参数数据类型）。 如果 BLOB 存储为文本（如 SQL Server text 字段），可以将 BLOB 作为字符串参数传递。 如果 BLOB 以二进制格式存储（如 SQL Server image 字段），可以将 byte 类型的数组作为二进制参数传递。
示例
下面的代码示例将员工信息添加到 Northwind 数据库中的 Employees 表。 它从文件中读取员工照片，并将它添加到表中的“照片”字段（图像字段）。
Public Shared Sub AddEmployee( _
lastName As String, _
firstName As String, _
title As String, _
hireDate As DateTime, _
reportsTo As Integer, _
photoFilePath As String, _
connectionString As String)
Dim photo() as Byte = GetPhoto(photoFilePath)
Using connection As SqlConnection = New SqlConnection( _
connectionString)
Dim command As SqlCommand = New SqlCommand( _
"INSERT INTO Employees (LastName, FirstName, Title, " & _
"HireDate, ReportsTo, Photo) " & _
"Values(@LastName, @FirstName, @Title, " & _
"@HireDate, @ReportsTo, @Photo)", connection)
command.Parameters.Add("@LastName", _
SqlDbType.NVarChar, 20).Value = lastName
command.Parameters.Add("@FirstName", _
SqlDbType.NVarChar, 10).Value = firstName
command.Parameters.Add("@Title", _
SqlDbType.NVarChar, 30).Value = title
command.Parameters.Add("@HireDate", _
SqlDbType.DateTime).Value = hireDate
command.Parameters.Add("@ReportsTo", _
SqlDbType.Int).Value = reportsTo
command.Parameters.Add("@Photo", _
SqlDbType.Image, photo.Length).Value = photo
connection.Open()
command.ExecuteNonQuery()
End Using
End Sub
Public Shared Function GetPhoto(filePath As String) As Byte()
Dim stream As FileStream = new FileStream( _
filePath, FileMode.Open, FileAccess.Read)
Dim reader As BinaryReader = new BinaryReader(stream)
Dim photo() As Byte = reader.ReadBytes(stream.Length)
reader.Close()
stream.Close()
Return photo
End Function
public static void AddEmployee(
string lastName,
string firstName,
string title,
DateTime hireDate,
int reportsTo,
string photoFilePath,
string connectionString)
{
byte[] photo = GetPhoto(photoFilePath);
using (SqlConnection connection = new SqlConnection(
connectionString))
SqlCommand command = new SqlCommand(
"INSERT INTO Employees (LastName, FirstName, " +
"Title, HireDate, ReportsTo, Photo) " +
"Values(@LastName, @FirstName, @Title, " +
"@HireDate, @ReportsTo, @Photo)", connection);
command.Parameters.Add("@LastName",
SqlDbType.NVarChar, 20).Value = lastName;
command.Parameters.Add("@FirstName",
SqlDbType.NVarChar, 10).Value = firstName;
command.Parameters.Add("@Title",
SqlDbType.NVarChar, 30).Value = title;
command.Parameters.Add("@HireDate",
SqlDbType.DateTime).Value = hireDate;
command.Parameters.Add("@ReportsTo",
SqlDbType.Int).Value = reportsTo;
command.Parameters.Add("@Photo",
SqlDbType.Image, photo.Length).Value = photo;
connection.Open();
command.ExecuteNonQuery();
}
}
public static byte[] GetPhoto(string filePath)
{
FileStream stream = new FileStream(
filePath, FileMode.Open, FileAccess.Read);
BinaryReader reader = new BinaryReader(stream);
byte[] photo = reader.ReadBytes((int)stream.Length);
reader.Close();
stream.Close();
return photo;
}