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1 using System; 2 using System.Data; 3 using System.Data.SQLite; 4 5 namespace SqliteConsoleApp 6 { 7 /// <summary> 8 /// SQLite 助手 9 /// </summary> 10 public sealed class SQLiteHelper 11 { 12 private const string ConnectionStr = "Data Source=recipes.s3db"; 13 private static SQLiteHelper _instance; 14 private static readonly object Locker = new object (); 15 16 private SQLiteHelper() 17 { 18 } 19 20 /// <summary> 21 /// 獲取實例 22 /// </summary> 23 /// <returns></returns> 24 public static SQLiteHelper GetInstance() 25 { 26 if (_instance == null ) 27 { 28 lock (Locker) 29 { 30 if (_instance == null ) 31 { 32 _instance = new SQLiteHelper (); 33 } 34 } 35 } 36 37 return _instance; 38 } 39 40 /// <summary> 41 /// 獲取數據表 42 /// </summary> 43 /// <param name="cmdText"> 需要執行的命令文本 </param> 44 /// <returns> 一個數據表集合 </returns> 45 public DataTable GetDataTable( string cmdText) 46 { 47 var dt = new DataTable(); 48 49 try 50 { 51 using (var conn = new SQLiteConnection (ConnectionStr)) 52 { 53 conn.Open(); 54 var cmd = new SQLiteCommand(conn) {CommandText = cmdText}; 55 using (var reader = cmd.ExecuteReader()) 56 { 57 dt.Load(reader); 58 } 59 } 60 } 61 catch (Exception e) 62 { 63 throw new Exception(e.Message); 64 } 65 66 return dt; 67 } 68 69 /// <summary> 70 /// 執行非查詢命令 71 /// </summary> 72 /// <param name="cmdText"> 需要執行的命令文本 </param> 73 /// <returns> 返回更新的行數 </returns> 74 public int ExecuteNonQuery( string cmdText) 75 { 76 using (var conn = new SQLiteConnection (ConnectionStr)) 77 { 78 conn.Open(); 79 var cmd = new SQLiteCommand(conn) {CommandText = cmdText}; 80 var rowsUpdated = cmd.ExecuteNonQuery(); 81 82 return rowsUpdated; 83 } 84 } 85 86 /// <summary> 87 /// 執行檢索單項命令 88 /// </summary> 89 /// <param name="cmdText"> 需要執行的命令文本 </param> 90 /// <returns> 一個字元串 </returns> 91 public string ExecuteScalar( string cmdText) 92 { 93 using (var conn = new SQLiteConnection (ConnectionStr)) 94 { 95 conn.Open(); 96 var cmd = new SQLiteCommand(conn) {CommandText = cmdText}; 97 var value = cmd.ExecuteScalar(); 98 99 if (value != null ) 100 { 101 return value.ToString(); 102 } 103 } 104 105 return "" ; 106 } 107 } 108 }