常用.net DB access 元件:
來源在此
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using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
namespace DbHelper
{
/// <summary>
/// 通用数据库访问类，封装了对数据库的常见操作
///</summary>
public sealed class DbUtility
{
public string ConnectionString { get; set; }
private DbProviderFactory providerFactory;
/// <summary>
/// 构造函数
/// </summary>
/// <param name="connectionString">数据库连接字符串</param>
/// <param name="providerType">数据库类型枚举，参见<paramref name="providerType"/></param>
public DbUtility(string connectionString, DbProviderType providerType)
{
ConnectionString = connectionString;
providerFactory = ProviderFactory.GetDbProviderFactory(providerType);
if (providerFactory == null)
{
throw new ArgumentException("Can't load DbProviderFactory for given value of providerType");
}
}
/// <summary>
/// 对数据库执行增删改操作，返回受影响的行数。
/// </summary>
/// <param name="sql">要执行的增删改的SQL语句</param>
/// <param name="parameters">执行增删改语句所需要的参数</param>
/// <returns></returns>
public int ExecuteNonQuery(string sql, IList<DbParameter> parameters)
{
return ExecuteNonQuery(sql, parameters, CommandType.Text);
}
/// <summary>
/// 对数据库执行增删改操作，返回受影响的行数。
/// </summary>
/// <param name="sql">要执行的增删改的SQL语句</param>
/// <param name="parameters">执行增删改语句所需要的参数</param>
/// <param name="commandType">执行的SQL语句的类型</param>
/// <returns></returns>
public int ExecuteNonQuery(string sql, IList<DbParameter> parameters, CommandType commandType)
{
using (DbCommand command = CreateDbCommand(sql, parameters, commandType))
{
command.Connection.Open();
int affectedRows = command.ExecuteNonQuery();
command.Connection.Close();
return affectedRows;
}
}
/// <summary>
/// 执行一个查询语句，返回一个关联的DataReader实例
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数</param>
/// <returns></returns>
public DbDataReader ExecuteReader(string sql, IList<DbParameter> parameters)
{
return ExecuteReader(sql, parameters, CommandType.Text);
}
/// <summary>
/// 执行一个查询语句，返回一个关联的DataReader实例
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数</param>
/// <param name="commandType">执行的SQL语句的类型</param>
/// <returns></returns>
public DbDataReader ExecuteReader(string sql, IList<DbParameter> parameters, CommandType commandType)
{
DbCommand command = CreateDbCommand(sql, parameters, commandType);
command.Connection.Open();
return command.ExecuteReader(CommandBehavior.CloseConnection);
}
/// <summary>
/// 执行一个查询语句，返回一个包含查询结果的DataTable
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数</param>
/// <returns></returns>
public DataTable ExecuteDataTable(string sql, IList<DbParameter> parameters)
{
return ExecuteDataTable(sql, parameters, CommandType.Text);
}
/// <summary>
/// 执行一个查询语句，返回一个包含查询结果的DataTable
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数</param>
/// <param name="commandType">执行的SQL语句的类型</param>
/// <returns></returns>
public DataTable ExecuteDataTable(string sql, IList<DbParameter> parameters, CommandType commandType)
{
using (DbCommand command = CreateDbCommand(sql, parameters, commandType))
{
using (DbDataAdapter adapter = providerFactory.CreateDataAdapter())
{
adapter.SelectCommand = command;
DataTable data = new DataTable();
adapter.Fill(data);
return data;
}
}
}
/// <summary>
/// 执行一个查询语句，返回查询结果的第一行第一列
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数</param>
/// <returns></returns>
public Object ExecuteScalar(string sql, IList<DbParameter> parameters)
{
return ExecuteScalar(sql, parameters, CommandType.Text);
}
/// <summary>
/// 执行一个查询语句，返回查询结果的第一行第一列
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数</param>
/// <param name="commandType">执行的SQL语句的类型</param>
/// <returns></returns>
public Object ExecuteScalar(string sql, IList<DbParameter> parameters, CommandType commandType)
{
using (DbCommand command = CreateDbCommand(sql, parameters, commandType))
{
command.Connection.Open();
object result = command.ExecuteScalar();
command.Connection.Close();
return result;
}
}
public DbParameter CreateDbParameter(string name, object value)
{
return CreateDbParameter(name, ParameterDirection.Input, value);
}
public DbParameter CreateDbParameter(string name, ParameterDirection parameterDirection, object value)
{
DbParameter parameter = providerFactory.CreateParameter();
parameter.ParameterName = name;
parameter.Value = value;
parameter.Direction = parameterDirection;
return parameter;
}
/// <summary>
/// 创建一个DbCommand对象
/// </summary>
/// <param name="sql">要执行的查询语句</param>
/// <param name="parameters">执行SQL查询语句所需要的参数</param>
/// <param name="commandType">执行的SQL语句的类型</param>
/// <returns></returns>
private DbCommand CreateDbCommand(string sql, IList<DbParameter> parameters, CommandType commandType)
{
DbConnection connection = providerFactory.CreateConnection();
DbCommand command = providerFactory.CreateCommand();
connection.ConnectionString = ConnectionString;
command.CommandText = sql;
command.CommandType = commandType;
command.Connection = connection;
if (!(parameters == null || parameters.Count == 0))
{
foreach (DbParameter parameter in parameters)
{
command.Parameters.Add(parameter);
}
}
return command;
}
}
/// <summary>
/// 数据库类型枚举
/// </summary>
public enum DbProviderType : byte
{
SqlServer,
MySql,
SQLite,
Oracle,
ODBC,
OleDb,
Firebird,
PostgreSql,
DB2,
Informix,
SqlServerCe
}
/// <summary>
/// DbProviderFactory工厂类
/// </summary>
public class ProviderFactory
{
private static Dictionary<DbProviderType, string> providerInvariantNames = new Dictionary<DbProviderType, string>();
private static Dictionary<DbProviderType, DbProviderFactory> providerFactoies = new Dictionary<DbProviderType, DbProviderFactory>(20);
static ProviderFactory()
{
//加载已知的数据库访问类的程序集
providerInvariantNames.Add(DbProviderType.SqlServer, "System.Data.SqlClient");
providerInvariantNames.Add(DbProviderType.OleDb, "System.Data.OleDb");
providerInvariantNames.Add(DbProviderType.ODBC, "System.Data.ODBC");
providerInvariantNames.Add(DbProviderType.Oracle, "Oracle.DataAccess.Client");
providerInvariantNames.Add(DbProviderType.MySql, "MySql.Data.MySqlClient");
providerInvariantNames.Add(DbProviderType.SQLite, "System.Data.SQLite");
providerInvariantNames.Add(DbProviderType.Firebird, "FirebirdSql.Data.Firebird");
providerInvariantNames.Add(DbProviderType.PostgreSql, "Npgsql");
providerInvariantNames.Add(DbProviderType.DB2, "IBM.Data.DB2.iSeries");
providerInvariantNames.Add(DbProviderType.Informix, "IBM.Data.Informix");
providerInvariantNames.Add(DbProviderType.SqlServerCe, "System.Data.SqlServerCe");
}
/// <summary>
/// 获取指定数据库类型对应的程序集名称
/// </summary>
/// <param name="providerType">数据库类型枚举</param>
/// <returns></returns>
public static string GetProviderInvariantName(DbProviderType providerType)
{
return providerInvariantNames[providerType];
}
/// <summary>
/// 获取指定类型的数据库对应的DbProviderFactory
/// </summary>
/// <param name="providerType">数据库类型枚举</param>
/// <returns></returns>
public static DbProviderFactory GetDbProviderFactory(DbProviderType providerType)
{
//如果还没有加载，则加载该DbProviderFactory
if (!providerFactoies.ContainsKey(providerType))
{
providerFactoies.Add(providerType, ImportDbProviderFactory(providerType));
}
return providerFactoies[providerType];
}
/// <summary>
/// 加载指定数据库类型的DbProviderFactory
/// </summary>
/// <param name="providerType">数据库类型枚举</param>
/// <returns></returns>
private static DbProviderFactory ImportDbProviderFactory(DbProviderType providerType)
{
string providerName = providerInvariantNames[providerType];
DbProviderFactory factory = null;
try
{
//从全局程序集中查找
factory = DbProviderFactories.GetFactory(providerName);
}
catch (ArgumentException e)
{
factory = null;
}
return factory;
}
}
}
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