数据库表结构:
IF EXISTS (SELECT name FROM sysobjects WHERE name = ''''Content'''' AND type = ''''U'''') DROP TABLE Content GO
create table Content ( --内容ID Id bigint IDENTITY(1,1) NOT NULL, --内容 data image default null, CONSTRAINT PK_ContentId PRIMARY KEY CLUSTERED (Id) )
GO
const String cnnstr = "Provider=SQLOLEDB.1;User ID=sa;Password=;Initial Catalog=MyDb;Data Source=(local)";
写入
public bool WriteContent(byte [] data) { OleDbConnection conn = new OleDbConnection(cnnstr); String mySelectQuery = "insert into Content(data)values(?)"; OleDbCommand myCommand = new OleDbCommand(mySelectQuery, conn); myCommand.CommandTimeout = 60; OleDbParameter param = new OleDbParameter("@data", OleDbType.VarBinary, data.Length); param.Direction = ParameterDirection.Input; param.Value = data; myCommand.Parameters.Add(param); bool ret = false;
try { conn.Open(); myCommand.ExecuteNonQuery(); ret = true; } catch(Exception e) { String msg = e.Message; } finally { //关闭数据库连接 if((conn != null) && (conn.State != ConnectionState.Closed)) { conn.Close(); } } return ret; }
读出
private byte [] ReadContent(Int64 contentId) { byte [] buff = null; OleDbConnection conn = new OleDbConnection(cnnstr ); String queryStr = String.Format("select data from Content where Id={0}", contentId); OleDbCommand myCommand = new OleDbCommand(queryStr, conn); myCommand.CommandTimeout = 60; OleDbDataReader reader = null; long dataLen = 0L; try { conn.Open(); reader = myCommand.ExecuteReader(); if( reader.Read() ) { //得到要读的数据长度,注意buff必须是空的引用 dataLen = reader.GetBytes(0, 0, buff, 0, 1); //分配缓冲区 buff = new byte[dataLen]; //读数据 dataLen = reader.GetBytes(0, 0, buff, 0, (int)dataLen); } } catch(Exception e) { internalError(e); String msg = e.Message; } finally { //关闭数据集 if(reader != null && !reader.IsClosed) reader.Close(); //关闭数据库连接 if((conn != null) && (conn.State != ConnectionState.Closed)) { conn.Close(); } } return buff; }
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