一个C#访问数据库的帮助类
using System;using System.Configuration;using System.Data;using System.Data.SqlClient;using System.Collections;namespace SQLHelperClass{ public abstract class SqlHelper { public static readonly string ConnectionStringMSSQL = ConfigurationManager.AppSettings["dbPath"].ToString(); private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable()); public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) { SqlCommand cmd = new SqlCommand(); using (SqlConnection conn = new SqlConnection(connectionString)) { PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters); int val = cmd.ExecuteNonQuery(); cmd.Parameters.Clear(); return val; } } 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; } 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; } public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) { SqlCommand cmd = new SqlCommand(); SqlConnection conn = new SqlConnection(connectionString); try { PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters); SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection); cmd.Parameters.Clear(); return rdr; } catch { conn.Close(); throw; } } public static DataSet ExecuteDataSet(string connectionString, string cmdText) { DataSet __ds = new DataSet(); try { SqlDataAdapter sda = new SqlDataAdapter(cmdText, connectionString); sda.Fill(__ds); } catch { throw; } return __ds; } public static DataSet ExecuteDataSet(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) { DataSet __ds = new DataSet(); SqlCommand cmd = new SqlCommand(); SqlConnection conn = new SqlConnection(connectionString); SqlDataAdapter sda = new SqlDataAdapter(); try { PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters); sda.SelectCommand = cmd; sda.Fill(__ds); cmd.Parameters.Clear(); return __ds; } catch { conn.Close(); throw; } } 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; } } 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; } public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters) { parmCache = commandParameters; } public static SqlParameter[] GetCachedParameters(string cacheKey) { SqlParameter[] cachedParms = (SqlParameter[])parmCache; if (cachedParms == null) return null; SqlParameter[] clonedParms = new SqlParameter; for (int i = 0, j = cachedParms.Length; i < j; i++) clonedParms = (SqlParameter)((ICloneable)cachedParms).Clone(); return clonedParms; } private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms) { if (conn.State != ConnectionState.Open) conn.Open(); cmd.Connection = conn; cmd.CommandText = cmdText; if (trans != null) cmd.Transaction = trans; cmd.CommandType = cmdType; if (cmdParms != null) { foreach (SqlParameter parm in cmdParms) cmd.Parameters.Add(parm); } } }}
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