/// <summary>
/// SqlHelper提供对于SqlClient常用功能封装提供高性能和高可扩展性的最佳实践
/// </summary>
public abstract class SqlHelper
{
//数据库连接字符串
public static readonly string sqlConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
// 使用哈希表存储缓存后的参数
private static Hashtable parmCache =
Hashtable.Synchronized(new Hashtable());
/// <summary>
/// 执行不返回的结果的SQL语句，依赖于特定的数据库连接和使用的提供者参数
/// </summary>
/// <remarks>
/// 示例:
/// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure,
/// "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="connectionString">为SqlConnection指定一个有效的连接字符串</param>
/// <param name="commandType">命令类型(stored procedure, text等等)</param>
/// <param name="commandText">存储过程名或T-SQL命令</param>
/// <param name="commandParameters">SqlParamters数组用于执行命令</param>
/// <returns>返回一个整型值得到影响的行数</returns>
public static int ExecuteNonQuery(string connectionString,
CommandType cmdType, string cmdText,
params SqlParameter[] commandParameters)
{
SqlCommand cmd = new SqlCommand(); //创建SqlCommand对象实例
//根据传入的连接字符串构建SqlConnection对象
using (SqlConnection conn = new SqlConnection(connectionString))
{
//根据传入的SqlParameter以及cmdType和cmdText构建SqlCommand命令
PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
int val = cmd.ExecuteNonQuery(); //执行SQL并返回受影响的行数
cmd.Parameters.Clear(); //清除参数集合
return val; //返回受影响的行数
}
}
/// <summary>
/// Execute a SqlCommand (that returns no resultset) against an existing database connection
/// using the provided parameters.
/// </summary>
/// <remarks>
/// e.g.:
/// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="conn">an existing database connection</param>
/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
/// <param name="commandText">the stored procedure name or T-SQL command</param>
/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
/// <returns>an int representing the number of rows affected by the command</returns>
public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
{
SqlCommand cmd = new SqlCommand();
PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
/// <summary>
/// Execute a SqlCommand (that returns no resultset) using an existing SQL Transaction
/// using the provided parameters.
/// </summary>
/// <remarks>
/// e.g.:
/// int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="trans">an existing sql transaction</param>
/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
/// <param name="commandText">the stored procedure name or T-SQL command</param>
/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
/// <returns>an int representing the number of rows affected by the command</returns>
public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
{
SqlCommand cmd = new SqlCommand();
PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
int val = cmd.ExecuteNonQuery();
cmd.Parameters.Clear();
return val;
}
/// <summary>
/// Execute a SqlCommand that returns a resultset against the database specified in the connection string
/// using the provided parameters.
/// </summary>
/// <remarks>
/// e.g.:
/// SqlDataReader r = ExecuteReader(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="connectionString">a valid connection string for a SqlConnection</param>
/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
/// <param name="commandText">the stored procedure name or T-SQL command</param>
/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
/// <returns>A SqlDataReader containing the results</returns>
public static SqlDataReader ExecuteReader(string connectionString,
CommandType cmdType, string cmdText,
params SqlParameter[] commandParameters)
{
SqlCommand cmd = new SqlCommand(); //实例化SqlCommand对象
SqlConnection conn = new SqlConnection(connectionString); //根据连接字符串实例化SqlConnection
try
{
//根据传入的SqlParameter数组及相关SQL参数设置SqlCommand属性
PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
//执行连接在执行完毕后关闭连接
SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
cmd.Parameters.Clear(); //清除参数列表
return rdr; //返回SqlDataReader对象
}
catch
{
conn.Close(); //在出现异常时即时关闭连接
throw; //重新抛出异常
}
}
public static DataTable ExecuteTable(string connectionString,
CommandType cmdType, string cmdText,
params SqlParameter[] commandParameters)
{
SqlCommand cmd = new SqlCommand(); //实例化SqlCommand对象
//根据指定的连接字符串创建SqlConnection对象
SqlConnection conn = new SqlConnection(connectionString);
DataSet ds = null;
try
{
//构建SqlCommand对象的相关属性
PrepareCommand(cmd, conn, null, cmdType,
cmdText, commandParameters);
//创建SqlDataAdapter实例，传入SqlCommand对象
SqlDataAdapter dp = new SqlDataAdapter(cmd);
ds = new DataSet();
dp.Fill(ds); //执行SQL语句并填充DataSet
}
catch
{
conn.Close(); //在出现异常时关闭连接
throw; //抛出异常
}
finally
{
if (conn != null) //无论是否出现异常，在离开时都要关闭连接
conn.Close();
}
//返回DataSet的第1个表
return (ds.Tables[0] != null) ? ds.Tables[0] : null;
}
/// <summary>
/// Execute a SqlCommand that returns the first column of the first record against the database specified in the connection string
/// using the provided parameters.
/// </summary>
/// <remarks>
/// e.g.:
/// Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="connectionString">a valid connection string for a SqlConnection</param>
/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
/// <param name="commandText">the stored procedure name or T-SQL command</param>
/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
/// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
{
SqlCommand cmd = new SqlCommand();
using (SqlConnection connection = new SqlConnection(connectionString))
{
PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
object val = cmd.ExecuteScalar();
cmd.Parameters.Clear();
return val;
}
}
/// <summary>
/// Execute a SqlCommand that returns the first column of the first record against an existing database connection
/// using the provided parameters.
/// </summary>
/// <remarks>
/// e.g.:
/// Object obj = ExecuteScalar(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
/// </remarks>
/// <param name="conn">an existing database connection</param>
/// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
/// <param name="commandText">the stored procedure name or T-SQL command</param>
/// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
/// <returns>An object that should be converted to the expected type using Convert.To{Type}</returns>
public static object ExecuteScalar(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
{
SqlCommand cmd = new SqlCommand();
PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
object val = cmd.ExecuteScalar();
cmd.Parameters.Clear();
return val;
}
/// <summary>
/// 添加参数数组到缓存
/// </summary>
/// <param name="cacheKey">参数缓存的键</param>
/// <param name="cmdParms">要被缓存的SqlParamters数组</param>
public static void CacheParameters(string cacheKey,
params SqlParameter[] commandParameters)
{
parmCache[cacheKey] = commandParameters; //添加到哈希表
}
/// <summary>
/// 获取缓存的参数数组
/// </summary>
/// <param name="cacheKey">用来查找缓存的参数的键</param>
/// <returns>缓存的SqlParamters数组</returns>
public static SqlParameter[] GetCachedParameters(string cacheKey)
{
SqlParameter[] cachedParms =
(SqlParameter[])parmCache[cacheKey]; //获取Sql参数数组
//如果当前缓存中并不存在参数数组，则返回null
if (cachedParms == null)
return null;
//实例化新的SqlParameter数组
SqlParameter[] clonedParms =
new SqlParameter[cachedParms.Length];
//将cachedParm表中缓存的参数赋给SqlParameter数组
for (int i = 0, j = cachedParms.Length; i < j; i++)
clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();
return clonedParms; //返回SqlCommand数组实例
}
/// <summary>
/// Prepare a command for execution
/// </summary>
/// <param name="cmd">SqlCommand object</param>
/// <param name="conn">SqlConnection object</param>
/// <param name="trans">SqlTransaction object</param>
/// <param name="cmdType">Cmd type e.g. stored procedure or text</param>
/// <param name="cmdText">Command text, e.g. Select * from Products</param>
/// <param name="cmdParms">SqlParameters to use in the command</param>
private static void PrepareCommand(SqlCommand cmd, SqlConnection conn,
SqlTransaction trans, CommandType cmdType,
string cmdText, SqlParameter[] cmdParms)
{
if (conn.State != ConnectionState.Open) //判断连接是否打开
conn.Open(); //打开连接
cmd.Connection = conn; //赋给SqlCommand连接对象
cmd.CommandText = cmdText; //指定连接文本
if (trans != null)
cmd.Transaction = trans; //是否开启事务
cmd.CommandType = cmdType; //指定命令类型
if (cmdParms != null)
{ //循环SqlParameter数组，添加到参数集合
foreach (SqlParameter parm in cmdParms)
cmd.Parameters.Add(parm);
}
}
}
