SQLite中的變量

Question

我想知道是否有一種已知技術用於在SqlLite數據庫中保存和使用變量。

我在尋找類似的$something變量可以甲骨文

下找到

Answer 1

沒有找到這方面的任何內置的解決方案，所以我通過具有關鍵的全局表解決了它，值對

這裏是我用來包裝這個很好的C＃類

public class SQLiteVariable 
{ 
    public SQLiteVariable() : this (null, string.Empty) 
    {} 
    public SQLiteVariable(SQLiteConnection connection) : this(connection, string.Empty) 
    {} 
    public SQLiteVariable(string name) : this(null, name) 
    {} 
    public SQLiteVariable(SQLiteConnection connection, string name) 
    { 
     Connection = connection; 
     Name = name; 
    } 

    /// <summary> 
    /// The table name used for storing the database variables 
    /// </summary> 
    private const string VariablesTable = "__GlobalDatabaseVariablesTable"; 

    /// <summary> 
    /// Gets or sets the SQLite database connection. 
    /// </summary> 
    /// <value>The connection.</value> 
    public SQLiteConnection Connection { get; set; } 

    /// <summary> 
    /// Gets or sets the SQLite variable name. 
    /// </summary> 
    /// <value>The name.</value> 
    public string Name { get; set; } 

    /// <summary> 
    /// Gets or sets the SQLite variable value. 
    /// </summary> 
    /// <value>The value.</value> 
    public string Value 
    { 
     get 
     { 
      CheckEnviornemnt(); 
      var cmd = new SQLiteCommand(Connection) 
          { 
           CommandText = "SELECT Value FROM " + VariablesTable + " WHERE Key=@VarName" 
          }; 
      cmd.Parameters.Add(new SQLiteParameter("@VarName", Name)); 
      var returnValue = cmd.ExecuteScalar(); 
      return returnValue as string; 
     } 
     set 
     { 
      CheckEnviornemnt(); 
      // Assume the variable exists and do an update 
      var cmd = new SQLiteCommand(Connection) 
      { 
       CommandText = "INSERT OR REPLACE INTO " + VariablesTable + " (Key, Value) VALUES(@VarName, @Value)" 
      }; 
      cmd.Parameters.Add(new SQLiteParameter("@Value", value)); 
      cmd.Parameters.Add(new SQLiteParameter("@VarName", Name)); 
      var count = cmd.ExecuteNonQuery(); 
     } 
    } 

    private void CheckEnviornemnt() 
    { 
     if (Connection == null) throw new ArgumentException("Connection was not initialized"); 
     var cmd = new SQLiteCommand(Connection) 
     { 
      CommandText = "CREATE TABLE IF NOT EXISTS "+VariablesTable+" (Key VARCHAR(30) PRIMARY KEY, Value VARCHAR(256));" 
     }; 
     cmd.ExecuteNonQuery(); 
    } 
}