C#使用 SQLite 数据库 开发的配置过程及基本操作类，实例程序：工商银行贵金属行情查看小工具

  1     public class SQLiteHelper
  2     {
  3         public SQLiteConnection Connection
  4         {
  5             get
  6             {
  7                 if (_cn == null)
  8                 {
  9                     Settings settings = new Settings();
 10                     string connection = settings.Connection.ToString();
 11                     _cn = new SQLiteConnection(connection);
 12                 }
 13                 return _cn;
 14             }
 15         }
 16 
 17         private SQLiteConnection _cn = null;
 18 
 19         public DataTable GetDataTable(string query)
 20         {
 21             DataTable dt = new DataTable();
 22             try
 23             {
 24                 Connection.Open();
 25                 GetAdapter(query).Fill(dt);
 26             }
 27             catch
 28             { }
 29             finally
 30             {
 31                 Connection.Close();
 32             }
 33             return dt;
 34         }
 35 
 36         public bool Update(string tableName, DataTable dt)
 37         {
 38             try
 39             {
 40                 Connection.Open();
 41                 string tableStructureQuery = string.Format("SELECT * FROM {0} WHERE 1 = 0", tableName);
 42                 SQLiteDataAdapter da = GetAdapter(tableStructureQuery);
 43                 da.Update(dt);
 44             }
 45             catch (Exception ex)
 46             {
 47                 MessageBox.Show(ex.Message);
 48             }
 49             finally
 50             {
 51                 Connection.Close();
 52             }
 53             return true;
 54         }
 55 
 56         public SQLiteDataAdapter GetAdapter(string query)
 57         {
 58             SQLiteCommand selectCommand = new SQLiteCommand(query, Connection);
 59             SQLiteDataAdapter adapter = new SQLiteDataAdapter(selectCommand);
 60             SQLiteCommandBuilder sb = new SQLiteCommandBuilder(adapter);
 61             return adapter;
 62         }
 63 
 64         public bool ExecuteScript(string query)
 65         {
 66             try
 67             {
 68                 SQLiteCommand selectCommand = new SQLiteCommand(query, Connection);
 69                 Connection.Open();
 70                 selectCommand.ExecuteNonQuery();
 71             }
 72             catch
 73             {
 74                 return false;
 75             }
 76             finally
 77             {
 78                 Connection.Close();
 79             }
 80 
 81             return true;
 82         }
 83     }
 84 
 85     public static class DataViewHelper
 86     {
 87         public static DataView Clone(this DataView source, string filter)
 88         {
 89             if (source == null)
 90             {
 91                 throw new ApplicationException("Source cannot be null");
 92             }
 93 
 94             DataView newView = new DataView(source.Table);
 95 
 96             string viewfilter = source.RowFilter;
 97 
 98             List<string> filters = new List<string>();
 99             if (!string.IsNullOrEmpty(viewfilter))
100                 filters.Add(string.Format("({0})", viewfilter));
101             if (!string.IsNullOrEmpty(filter))
102                 filters.Add(string.Format("({0})", filter));
103 
104             newView.RowFilter = string.Join(" AND ", filters.ToArray());
105 
106             return newView;
107         }
108 
109         public static DataView Clone(this DataView source)
110         {
111             return source.Clone(string.Empty);
112         }
113     }

 1    public  class DAO : SQLiteHelper
 2     {
 3         public DAO(string tableName)
 4         {
 5             TableName = tableName;
 6         }
 7         public string SelectTableQuery { get { return "SELECT * FROM " + TableName; } }
 8 
 9          public string TableStructureQuery { get { return SelectTableQuery + " WHERE 1=0"; } }
10 
11          public int GetMaxID(string fieldName)
12          {14              StringBuilder commandText = new StringBuilder();
15              commandText.AppendLine(string.Format(@"SELECT MAX({0}) ", fieldName));
16              commandText.AppendLine(string.Format(@" FROM {0} ", TableName));
17              DataTable dt = GetDataTable(commandText.ToString());
18              if (dt.Rows.Count == 0)
19                  return 0;
20              else
21                  return int.Parse(dt.Rows[0][0].ToString());
22          }
23 
24         public string TableName { get; set; }
25 
26         internal DataTable GetDataTableStructor()
27         {
28             return GetDataTable(TableStructureQuery);
29         }
30 
31         public bool Update(DataTable dt)
32         {
33             return base.Update(TableName, dt);
34         }
35     }