连接就使用SqlConnection类连接，Connection.Open()打开数据库连接。
使用SqlCommand类操作，有三个属性：（1）Command.Connection。这个就是使用刚刚打开的Connection类。（2）Command.CommandText，设置SQL语言。（3）Command.CommandType，设置CommandText的属性。
最后执行Command。完成操作。
发个例子吧：
你的代码是什么问题呢？
网上很多例子啊，前提是你的sql server数据库也要设置好才行。
你的代码是什么问题呢？
网上很多例子啊，前提是你的sql server数据库也要设置好才行。
http://www.cnblogs.com/bluestorm/p/3368466.html
http://blog.csdn.net/kkkkkxiaofei/article/details/7904569
参考下
关键是你的连接字符串和 sql server 的配置是否正确。
config 配置
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Configuration;
using System.Data.SqlClient;
using System.Text;
namespace MonitorServiceClass.SQLService
{
public enum Conditional
{
AND,
OR
}
public class SqlHelper
{
public static string myConnection = ConfigurationManager.ConnectionStrings["conn"].ToString();
public static string Error = null;
public SqlHelper()
{
//InitConnection();
}
public void InitConnection()
{
try
{
SqlConnection conn = new SqlConnection(myConnection);
conn.Open();
}
catch (Exception e)
{
Console.WriteLine("concetion is fail " +e.Message );
}
}
/// <summary>
/// 插入一条数据
/// </summary>
/// <param name="tableName">表名</param>
/// <param name="dataMap">数据（列名，值）</param>
/// <returns></returns>
public static bool InsertData(string tableName, Dictionary<string, string> dataMap)
{
Error = null;
bool isOk = false;
StringBuilder myStr = new StringBuilder();
try
{
myStr.Append("insert into ");
myStr.Append(tableName);
myStr.Append(" (");
foreach (KeyValuePair<string,string> kvp in dataMap)
{
myStr.Append(kvp.Key);
myStr.Append(",");
}
myStr.Remove(myStr.Length - 1, 1);
myStr.Append(")");
myStr.Append(" values ");
myStr.Append(" (");
foreach (KeyValuePair<string,string> kvp in dataMap)
{
myStr.Append("'");
myStr.Append(kvp.Value);
myStr.Append("'");
myStr.Append(",");
}
myStr.Remove(myStr.Length - 1, 1);
myStr.Append(")");
int num = ExecuteNonQuery(myStr.ToString());
if (num > 0)
{
isOk = true;
}
}
catch (Exception e)
{
Error = e.Message.ToString();
}
finally
{
myStr = null;
}
return isOk;
}
/// <summary>
/// 更新表中的数据
/// </summary>
/// <param name="tableName">表名</param>
/// <param name="dataMap">数据（列名，值）</param>
/// <param name="selectKey">选择的列名</param>
/// <param name="selectValue">选择的值</param>
/// <returns>判断是否更新数据成功</returns>
public static bool UpdateData(string tableName, Dictionary<string, string> dataMap,string selectKey,string selectValue)
{
Error = null;
bool isOk = false;
StringBuilder myStr = new StringBuilder();
try
{
myStr.Append("update ");
myStr.Append(tableName);
myStr.Append(" set ");
foreach(KeyValuePair<string,string> kvp in dataMap)
{
myStr.Append(kvp.Key);
myStr.Append(" = ");
myStr.Append("'");
myStr.Append(kvp.Value);
myStr.Append("',");
}
myStr.Remove(myStr.Length - 1, 1);
myStr.Append(" where ");
myStr.Append(selectKey);
myStr.Append(" = ");
myStr.Append("'");
myStr.Append(selectValue);
myStr.Append("'");
int num = ExecuteNonQuery(myStr.ToString());
if(num > 0)
isOk = true;
}
catch (Exception e)
{
Error = e.Message.ToString();
}
finally
{
myStr = null;
}
return isOk;
}
/// <summary>
/// 删除指定的数据
/// </summary>
/// <param name="tableName">表名</param>
/// <param name="dataMap">数据（列名，值）</param>
/// <param name="operate">逻辑操作符</param>
/// <returns></returns>
public static bool DeleteData(string tableName, Dictionary<string,string> dataMap,Conditional operate)
{
Error = null;
bool isOk = false;
StringBuilder myStr = new StringBuilder();
try
{
myStr.Append("delete from ");
myStr.Append(tableName);
myStr.Append(" where ");
if (operate == Conditional.AND)
{
foreach (KeyValuePair<string, string> kvp in dataMap)
{
myStr.Append(kvp.Key);
myStr.Append(" = ");
myStr.Append("'");
myStr.Append(kvp.Value);
myStr.Append("'");
myStr.Append(" and ");
}
myStr.Remove(myStr.Length - 4, 4);
}
else
{
foreach (KeyValuePair<string, string> kvp in dataMap)
{
myStr.Append(kvp.Key);
myStr.Append(" = ");
myStr.Append("'");
myStr.Append(kvp.Value);
myStr.Append("'");
myStr.Append(" or ");
}
myStr.Remove(myStr.Length - 3, 3);
}
int num = ExecuteNonQuery(myStr.ToString());
if (num > 0)
isOk = true;
}
catch (Exception e)
{
Error = e.Message.ToString();
}
finally
{
myStr = null;
}
return isOk;
}
/// <summary>
/// 按sql查询
/// </summary>
/// <param name="sqlString"></param>
/// <returns></returns>
public static DataTable QueryBySql(string sqlString)
{
try
{
return ExecuteTable(sqlString);
}
catch (SqlException ex)
{
Error = ex.Message.ToString();
return null;
}
}
public static DataTable ExecuteTable(string cmdText)
{
using (SqlConnection conn = new SqlConnection(myConnection))
{
conn.Open();
SqlDataAdapter adp = new SqlDataAdapter(cmdText, conn);
DataSet ds = new DataSet();
adp.Fill(ds);
conn.Close();
return ds.Tables[0];
}
}
public static void UpdateDataSet(DataTable dt, string strSql)
{
using (SqlConnection conn = new SqlConnection(myConnection))
{
try
{
conn.Open();
SqlDataAdapter command = new SqlDataAdapter(strSql, conn);
SqlCommandBuilder cmd = new SqlCommandBuilder(command);
command.Update(dt);
}
catch (SqlException ex)
{
Error = ex.Message.ToString();
}
finally
{
if (conn.State != ConnectionState.Closed)
{
conn.Close();
}
}
}
}
public static void InsertDataSet(DataTable dt, string strSql)
{
using (SqlConnection conn = new SqlConnection(myConnection))
{
try
{
conn.Open();
SqlDataAdapter adapter = new SqlDataAdapter(strSql, conn);
SqlCommandBuilder commandBuilder = new SqlCommandBuilder(adapter);
adapter.InsertCommand = commandBuilder.GetInsertCommand();
adapter.Update(dt);
dt.AcceptChanges();
}
catch (SqlException ex)
{
Error = ex.Message.ToString();
}
finally
{
if (conn.State != ConnectionState.Closed)
{
conn.Close();
}
}
}
}
/// <summary>
/// 用于执行 Update,Insert,Delete语句时候, 返回操作影响的行数
/// </summary>
/// <param name="sqlString">sql执行语句</param>
/// <returns>返回受影响的行数</returns>
public static int ExecuteNonQuery(string sqlString)
{
Error = null;
using (SqlConnection conn = new SqlConnection(myConnection))
{
int rows = 0;
using( SqlCommand command = new SqlCommand(sqlString, conn))
try
{
conn.Open();
rows = command.ExecuteNonQuery();
return rows;
}
catch (SqlException ex)
{
Error = ex.Message.ToString();
}
finally
{
if (conn.State != ConnectionState.Closed)
{
conn.Close();
}
}
return rows;
}
}
/// <summary>
/// 用于执行其它sql语句操作时候，返回DataSet 数据
/// </summary>
/// <param name="sqlString">执行的Sql语句</param>
/// <returns>返回的DataSet</returns>
public static DataSet ExecuteQuery(string sqlString)
{
Error = null;
using (SqlConnection conn = new SqlConnection(myConnection))
{
DataSet ds = new DataSet();
try
{
conn.Open();
SqlDataAdapter adp = new SqlDataAdapter(sqlString, conn);
adp.Fill(ds, "ds");
return ds;
}
catch (SqlException ex)
{
Error = ex.Message.ToString();
}
finally
{
if (conn.State != ConnectionState.Closed)
{
conn.Close();
}
}
return null;
}
}
/// <summary>
/// 对于其它操作的返回值，通过转换来获取受影响的行数来判断是否操作成功
/// </summary>
/// <param name="ds">DataSet</param>
/// <returns>返回受影响的行数</returns>
public static int AffectLineAmount(DataSet ds)
{
if (ds == null)
return 0;
else
{
int count = ds.Tables[0].Rows.Count;
return count;
}
}
}
}