SQLiteHelper

本文定义了一个DBHelper类，是SQLite的。需要添加一个System.Data.SQLite的dll，可以到SQLite的官网下载。类的代码如下

  1 using System;

  2 using System.Data;

  3 using System.Data.SQLite;

  4 using System.Configuration;

  5 using System.Collections;

  6 

  7 namespace Common

  8 {

  9     public abstract class SQLiteHelper

 10     {

 11         //Data Source=db file fullname

 12         public static readonly string connectionstring = ConfigurationManager.AppSettings["connectionstring"];

 13 

 14         private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());

 15 

 16         public static int ExecuteNonQuery(string connectionstring, CommandType commandType, string commandText, params SQLiteParameter[] commandParameters)

 17         {

 18             SQLiteCommand cmd = new SQLiteCommand();

 19             using (SQLiteConnection cn=new SQLiteConnection(connectionstring))

 20             {

 21                 PrepareCommand(cmd, cn, null, commandType, commandText, commandParameters);

 22                 int result = cmd.ExecuteNonQuery();

 23                 cmd.Parameters.Clear();

 24                 return result;

 25             }

 26         }

 27 

 28         public static int ExecuteNonQuery(SQLiteConnection connection, CommandType commandType, string commandText, params SQLiteParameter[] commandParameters)

 29         {

 30             SQLiteCommand cmd = new SQLiteCommand();

 31 

 32             PrepareCommand(cmd, connection, null, commandType, commandText, commandParameters);

 33             int result = cmd.ExecuteNonQuery();

 34             cmd.Parameters.Clear();

 35             return result;

 36         }

 37 

 38         public static int ExecuteNonQuery(SQLiteTransaction trans, CommandType commandType, string commandText, params SQLiteParameter[] commandParameters)

 39         {

 40             SQLiteCommand cmd = new SQLiteCommand();

 41 

 42             PrepareCommand(cmd, trans.Connection, trans, commandType, commandText, commandParameters);

 43             int result = cmd.ExecuteNonQuery();

 44             cmd.Parameters.Clear();

 45             return result;

 46         }

 47 

 48         public static SQLiteDataReader ExecuteReader(string connectionstring,CommandType commandType,string commandText,params SQLiteParameter [] commandParameters)

 49         {

 50             SQLiteCommand cmd = new SQLiteCommand();

 51             SQLiteConnection cn=new SQLiteConnection(connectionstring);

 52             

 53             try

 54             {

 55                 PrepareCommand(cmd, cn, null, commandType, commandText, commandParameters);

 56                 SQLiteDataReader result = null;

 57                 result = cmd.ExecuteReader(CommandBehavior.CloseConnection);

 58                 cmd.Parameters.Clear();

 59                 return result;

 60             }

 61             catch 

 62             {

 63                 cn.Close();

 64                 throw;

 65             }

 66             

 67         }

 68 

 69         public static object ExecuteScalar(string connectionstring, CommandType commandType, string commandText, params SQLiteParameter[] commandParameters)

 70         {

 71             SQLiteCommand cmd = new SQLiteCommand();

 72 

 73             using (SQLiteConnection cn=new SQLiteConnection(connectionstring))

 74             {

 75                 PrepareCommand(cmd, cn, null, commandType, commandText, commandParameters);

 76                 object result = cmd.ExecuteScalar();

 77                 cmd.Parameters.Clear();

 78                 return result;

 79             }

 80         }

 81 

 82         public static object ExecuteScalar(SQLiteConnection connection, CommandType commandType, string commandText, params SQLiteParameter[] commandParameters)

 83         {

 84             SQLiteCommand cmd = new SQLiteCommand();

 85 

 86             PrepareCommand(cmd, connection, null, commandType, commandText, commandParameters);

 87             object result = cmd.ExecuteScalar();

 88             cmd.Parameters.Clear();

 89             return result;

 90         }

 91 

 92         public static void CacheParameters(string cacheKey, params SQLiteParameter[] commandParameters)

 93         {

 94             parmCache[cacheKey] = commandParameters;

 95         }

 96 

 97         public static SQLiteParameter[] GetCacheParameters(string cacheKey)

 98         {

 99             SQLiteParameter[] cacheParams = (SQLiteParameter[])parmCache[cacheKey];

100 

101             if (cacheParams == null) return null;

102 

103             int cacheLength=cacheParams.Length;

104             SQLiteParameter[] cloneParams=new SQLiteParameter[cacheLength];

105 

106             for (int i = 0; i < cacheLength; i++)

107                 cloneParams[i] = (SQLiteParameter)((ICloneable)cacheParams[i]).Clone();

108 

109             return cloneParams;

110         }

111 

112         private static void PrepareCommand(SQLiteCommand command, SQLiteConnection connection, SQLiteTransaction trans, CommandType commandType, string commandText, SQLiteParameter[] commandParameters)

113         {

114             command.Connection = connection;

115             command.CommandType = commandType;

116             command.CommandText = commandText;

117 

118             if (commandParameters != null) 

119                 command.Parameters.AddRange(commandParameters);

120 

121             if (trans != null)

122                 command.Transaction = trans;

123 

124             if (connection.State != ConnectionState.Open)

125                 connection.Open();

126         }

127     }

128 }