正文

C#实现Access通用访问类OleDbHelper完整实例

︶ㄣ速达网 メ
米米素材网V管理员 / 阅读
0708

这篇文章主要介绍了C#实现Access通用访问类OleDbHelper,结合完整实例形式分析了C#针对access数据库的连接、查询、遍历、分页显示等相关操作技巧,需要的朋友可以参考下

本文实例讲述了C#实现Access通用访问类OleDbHelper。分享给大家供大家参考，具体如下：

最近在做一个项目数据库用的是Access,第一次使用Access数据库，刚开始做有些不顺，数据库的操作和SqlServer稍有些不同，而异常跟踪得到的信息也没有什么意义，经过几天的反复寻找问题，总算解决了一些问题，为了访问Access 数据库，我写了一个用于专门访问的类来操作数据库，其中包括，执行数据库命令，返回 DataSet，返回单条记录，返回DataReader，通用分页方法等几个常用的的操作方法。请各位提出意见，以便我完善这个类。虽是参考SqlHelper 但是比其简单的多，所有的代码如下：

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.Common;
using System.Data.OleDb;
namespace Common
{
  /// <summary>
  /// OleDb 书库访问类
  /// </summary>
  public static class OleDbHelper
  {
    /// <summary>
    /// Access 的数据库连接字符串格式.
    /// </summary>
    public const string ACCESS_CONNECTIONSTRING_TEMPLATE = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};";
    // Hashtable to store cached parameters
    private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());
    /// <summary>
    /// 针对 System.Data.OleDb.OleDbCommand.Connection 执行 SQL 语句并返回受影响的行数.
    /// </summary>
    /// <param name="connString"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static int ExecuteNonQuery(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      using (OleDbConnection conn = new OleDbConnection(connString))
      {
        PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
        int val = cmd.ExecuteNonQuery();
        cmd.Parameters.Clear();
        return val;
      }
    }
    /// <summary>
    /// 针对 System.Data.OleDb.OleDbCommand.Connection 执行 SQL 语句并返回受影响的行数.
    /// </summary>
    /// <param name="conn"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static int ExecuteNonQuery(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
      int val = cmd.ExecuteNonQuery();
      cmd.Parameters.Clear();
      return val;
    }
    /// <summary>
    /// 针对 System.Data.OleDb.OleDbCommand.Connection 执行 SQL 语句并返回受影响的行数.
    /// </summary>
    /// <param name="trans"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static int ExecuteNonQuery(OleDbTransaction trans, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, cmdParms, ConnectionActionType.None);
      int val = cmd.ExecuteNonQuery();
      cmd.Parameters.Clear();
      return val;
    }
    /// <summary>
    /// 将 System.Data.OleDb.OleDbCommand.CommandText 发送到 System.Data.OleDb.OleDbCommand.Connection 并生成一个 System.Data.OleDb.OleDbDataReader.
    /// </summary>
    /// <param name="connString"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static OleDbDataReader ExecuteReader(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      OleDbConnection conn = new OleDbConnection(connString);
      try
      {
        PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
        OleDbDataReader rdr = cmd.ExecuteReader();
        cmd.Parameters.Clear();
        return rdr;
      }
      catch
      {
        conn.Close();
        throw;
      }
    }
    /// <summary>
    /// 将 System.Data.OleDb.OleDbCommand.CommandText 发送到 System.Data.OleDb.OleDbCommand.Connection 并生成一个 System.Data.OleDb.OleDbDataReader.
    /// </summary>
    /// <param name="conn"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static OleDbDataReader ExecuteReader(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      try
      {
        PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
        OleDbDataReader rdr = cmd.ExecuteReader();
        cmd.Parameters.Clear();
        return rdr;
      }
      catch
      {
        conn.Close();
        throw;
      }
    }
    /// <summary>
    /// 执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行.
    /// </summary>
    /// <param name="connString"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static object ExecuteScalar(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      using (OleDbConnection conn = new OleDbConnection(connString))
      {
        PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
        object val = cmd.ExecuteScalar();
        cmd.Parameters.Clear();
        return val;
      }
    }
    /// <summary>
    /// 执行查询，并返回查询所返回的结果集中第一行的第一列。忽略其他列或行.
    /// </summary>
    /// <param name="conn"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static object ExecuteScalar(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
      object val = cmd.ExecuteScalar();
      cmd.Parameters.Clear();
      return val;
    }
    /// <summary>
    /// 执行查询，并返回查询所返回的结果数据集.
    /// </summary>
    /// <param name="connString"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static DataSet ExecuteDataset(string connString, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      using (OleDbConnection conn = new OleDbConnection(connString))
      {
        PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.Open);
        OleDbDataAdapter da = new OleDbDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        cmd.Parameters.Clear();
        return ds;
      }
    }
    /// <summary>
    /// 执行查询，并返回查询所返回的结果数据集.
    /// </summary>
    /// <param name="conn"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <returns></returns>
    public static DataSet ExecuteDataset(OleDbConnection conn, CommandType cmdType, string cmdText, params OleDbParameter[] cmdParms)
    {
      OleDbCommand cmd = new OleDbCommand();
      PrepareCommand(cmd, conn, null, cmdType, cmdText, cmdParms, ConnectionActionType.AutoDetection);
      OleDbDataAdapter da = new OleDbDataAdapter(cmd);
      DataSet ds = new DataSet();
      da.Fill(ds);
      cmd.Parameters.Clear();
      return ds;
    }
    /// <summary>
    /// 缓存查询的 OleDb 参数对象.
    /// </summary>
    /// <param name="cacheKey"></param>
    /// <param name="cmdParms"></param>
    public static void CacheParameters(string cacheKey, params OleDbParameter[] cmdParms)
    {
      parmCache[cacheKey] = cmdParms;
    }
    /// <summary>
    /// 从缓存获取指定的参数对象数组.
    /// </summary>
    /// <param name="cacheKey"></param>
    /// <returns></returns>
    public static OleDbParameter[] GetCachedParameters(string cacheKey)
    {
      OleDbParameter[] cachedParms = (OleDbParameter[])parmCache[cacheKey];
      if (cachedParms == null)
        return null;
      OleDbParameter[] clonedParms = new OleDbParameter[cachedParms.Length];
      for (int i = 0, j = cachedParms.Length; i < j; i++)
        clonedParms[i] = (OleDbParameter)((ICloneable)cachedParms[i]).Clone();
      return clonedParms;
    }
    /// <summary>
    /// 准备命令对象.
    /// </summary>
    /// <param name="cmd"></param>
    /// <param name="conn"></param>
    /// <param name="trans"></param>
    /// <param name="cmdType"></param>
    /// <param name="cmdText"></param>
    /// <param name="cmdParms"></param>
    /// <param name="connActionType"></param>
    private static void PrepareCommand(OleDbCommand cmd, OleDbConnection conn, OleDbTransaction trans, CommandType cmdType, string cmdText, OleDbParameter[] cmdParms, ConnectionActionType connActionType)
    {
      if (connActionType == ConnectionActionType.Open)
      {
        conn.Open();
      }
      else
      {
        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 (OleDbParameter parm in cmdParms)
          cmd.Parameters.Add(parm);
      }
    }
    /// <summary>
    /// 统一分页显示数据记录
    /// </summary>
    /// <param name="connString">数据库连接字符串</param>
    /// <param name="pageIndex">当前页码</param>
    /// <param name="pageSize">每页显示的条数</param>
    /// <param name="fileds">显示的字段</param>
    /// <param name="table">查询的表格</param>
    /// <param name="where">查询的条件</param>
    /// <param name="order">排序的规则</param>
    /// <param name="pageCount">out：总页数</param>
    /// <param name="recordCount">out：总条数</param>
    /// <param name="id">表的主键</param>
    /// <returns>返回DataTable集合</returns>
    public static DataTable ExecutePager(string connString, int pageIndex, int pageSize, string fileds, string table, string where, string order, out int pageCount, out int recordCount, string id)
    {
      if (pageIndex < 1) pageIndex = 1;
      if (pageSize < 1) pageSize = 10;
      if (string.IsNullOrEmpty(fileds)) fileds = "*";
      if (string.IsNullOrEmpty(order)) order = "ID desc";
      using (OleDbConnection conn = new OleDbConnection(connString))
      {
        string myVw = string.Format(" {0} ", table);
        string sqlText = string.Format(" select count(0) as recordCount from {0} {1}", myVw, where);
        OleDbCommand cmdCount = new OleDbCommand(sqlText, conn);
        if (conn.State == ConnectionState.Closed)
          conn.Open();
        recordCount = Convert.ToInt32(cmdCount.ExecuteScalar());
        if ((recordCount % pageSize) > 0)
          pageCount = recordCount / pageSize + 1;
        else
          pageCount = recordCount / pageSize;
        OleDbCommand cmdRecord;
        if (pageIndex == 1)//第一页
        {
          cmdRecord = new OleDbCommand(string.Format("select top {0} {1} from {2} {3} order by {4} ", pageSize, fileds, myVw, where, order), conn);
        }
        else if (pageIndex > pageCount)//超出总页数
        {
          cmdRecord = new OleDbCommand(string.Format("select top {0} {1} from {2} {3} order by {4} ", pageSize, fileds, myVw, "where 1=2", order), conn);
        }
        else
        {
          int pageLowerBound = pageSize * pageIndex;
          int pageUpperBound = pageLowerBound - pageSize;
          string recordIDs = RecordID(string.Format("select top {0} {1} from {2} {3} order by {4} ", pageLowerBound, id, myVw, where, order), pageUpperBound, conn);
          cmdRecord = new OleDbCommand(string.Format("select {0} from {1} where {4} in ({2}) order by {3} ", fileds, myVw, recordIDs, order, id), conn);
        }
        OleDbDataAdapter dataAdapter = new OleDbDataAdapter(cmdRecord);
        DataTable dt = new DataTable();
        dataAdapter.Fill(dt);
        return dt;
      }
    }
    private static string RecordID(string query, int passCount, OleDbConnection conn)
    {
      OleDbCommand cmd = new OleDbCommand(query, conn);
      string result = string.Empty;
      using (IDataReader dr = cmd.ExecuteReader())
      {
        while (dr.Read())
        {
          if (passCount < 1)
          {
            result += "," + dr.GetInt32(0);
          }
          passCount--;
        }
      }
      return result.Substring(1);
    }
    /// <summary>
    /// 连接操作类型枚举.
    /// </summary>
    enum ConnectionActionType
    {
      None = 0,
      AutoDetection = 1,
      Open = 2
    }
  }
}

希望本文所述对大家C#程序设计有所帮助。