sqlitedatareader.cs

来自「sqlite 3.3.8 支持加密的版本」· CS 代码 · 共 870 行 · 第 1/3 页

            }
          }

          // Determine IsUnique properly, which is a pain in the butt!
          if (wantUniqueInfo)
          {
            if ((string)row[SchemaTableOptionalColumn.BaseCatalogName] != strCatalog
              || (string)row[SchemaTableColumn.BaseTableName] != strTable)
            {
              strCatalog = (string)row[SchemaTableOptionalColumn.BaseCatalogName];
              strTable = (string)row[SchemaTableColumn.BaseTableName];

              tblIndexes = _command.Connection.GetSchema("Indexes", new string[] {
                (string)row[SchemaTableOptionalColumn.BaseCatalogName],
                null,
                (string)row[SchemaTableColumn.BaseTableName],
                null });
            }

            foreach (DataRow rowIndexes in tblIndexes.Rows)
            {
              tblIndexColumns = _command.Connection.GetSchema("IndexColumns", new string[] {
                (string)row[SchemaTableOptionalColumn.BaseCatalogName],
                null,
                (string)row[SchemaTableColumn.BaseTableName],
                (string)rowIndexes["INDEX_NAME"],
                null
                });
              foreach (DataRow rowColumnIndex in tblIndexColumns.Rows)
              {
                if (String.Compare((string)rowColumnIndex["COLUMN_NAME"], strColumn, true, CultureInfo.InvariantCulture) == 0)
                {
                  if (tblIndexColumns.Rows.Count == 1) row[SchemaTableColumn.IsUnique] = rowIndexes["UNIQUE"];
                  break;
                }
              }
            }
          }
        }
        
        if (String.IsNullOrEmpty(dataType))
        {
          TypeAffinity affin;
          dataType = _activeStatement._sql.ColumnType(_activeStatement, n, out affin);
        }

        if (String.IsNullOrEmpty(dataType) == false)
          row["DataTypeName"] = dataType;

        tbl.Rows.Add(row);
      }

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Retrieves the column as a string
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>string</returns>
    public override string GetString(int i)
    {
      VerifyType(i, DbType.String);
      return _activeStatement._sql.GetText(_activeStatement, i);
    }

    /// <summary>
    /// Retrieves the column as an object corresponding to the underlying datatype of the column
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>object</returns>
    public override object GetValue(int i)
    {
      CheckClosed();

      SQLiteType typ = GetSQLiteType(i);
      typ.Affinity = _activeStatement._sql.ColumnAffinity(_activeStatement, i);
      return _activeStatement._sql.GetValue(_activeStatement, i, ref typ);
    }

    /// <summary>
    /// Retreives the values of multiple columns, up to the size of the supplied array
    /// </summary>
    /// <param name="values">The array to fill with values from the columns in the current resultset</param>
    /// <returns>The number of columns retrieved</returns>
    public override int GetValues(object[] values)
    {
      CheckClosed();

      SQLiteType typ;
      int nMax = _fieldCount;
      if (values.Length < nMax) nMax = values.Length;


      for (int n = 0; n < nMax; n++)
      {
        typ = GetSQLiteType(n);
        typ.Affinity = _activeStatement._sql.ColumnAffinity(_activeStatement, n);
        values[n] = _activeStatement._sql.GetValue(_activeStatement, n, ref typ);
      }

      return nMax;
    }

    /// <summary>
    /// Returns True if the resultset has rows that can be fetched
    /// </summary>
    public override bool HasRows
    {
      get
      {
        CheckClosed();
        return (_readingState != 1);
      }
    }

    /// <summary>
    /// Returns True if the data reader is closed
    /// </summary>
    public override bool IsClosed
    {
      get { return (_command == null); }
    }

    /// <summary>
    /// Returns True if the specified column is null
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>True or False</returns>
    public override bool IsDBNull(int i)
    {
      CheckClosed();
      return _activeStatement._sql.IsNull(_activeStatement, i);
    }

    /// <summary>
    /// Moves to the next resultset in multiple row-returning SQL command.
    /// </summary>
    /// <returns>True if the command was successful and a new resultset is available, False otherwise.</returns>
    public override bool NextResult()
    {
      CheckClosed();

      SQLiteStatement stmt = null;
      int fieldCount;

      while (true)
      {
        if (_activeStatement != null && stmt == null)
        {
          // Reset the previously-executed statement
          _activeStatement._sql.Reset(_activeStatement);
          
          // If we're only supposed to return a single rowset, step through all remaining statements once until
          // they are all done and return false to indicate no more resultsets exist.
          if ((_commandBehavior & CommandBehavior.SingleResult) != 0)
          {
            for (; ; )
            {
              stmt = _command.GetStatement(_activeStatementIndex + 1);
              if (stmt == null) break;
              _activeStatementIndex++;

              stmt._sql.Step(stmt);
              if (stmt._sql.ColumnCount(stmt) == 0)
              {
                if (_rowsAffected == -1) _rowsAffected = 0;
                _rowsAffected += stmt._sql.Changes;
              }
              stmt._sql.Reset(stmt); // Gotta reset after every step to release any locks and such!
            }
            return false;
          }
        }

        // Get the next statement to execute
        stmt = _command.GetStatement(_activeStatementIndex + 1);

        // If we've reached the end of the statements, return false, no more resultsets
        if (stmt == null)
          return false;

        // If we were on a current resultset, set the state to "done reading" for it
        if (_readingState < 1)
          _readingState = 1;

        _activeStatementIndex++;

        fieldCount = stmt._sql.ColumnCount(stmt);

        // If the statement is not a select statement or we're not retrieving schema only, then perform the initial step
        if ((_commandBehavior & CommandBehavior.SchemaOnly) == 0 || fieldCount == 0)
        {
          if (stmt._sql.Step(stmt))
          {
            _readingState = -1;
          }
          else if (fieldCount == 0) // No rows returned, if fieldCount is zero, skip to the next statement
          {
            if (_rowsAffected == -1) _rowsAffected = 0;
            _rowsAffected += stmt._sql.Changes;
            stmt._sql.Reset(stmt);
            continue; // Skip this command and move to the next, it was not a row-returning resultset
          }
          else // No rows, fieldCount is non-zero so stop here
          {
            _readingState = 1; // This command returned columns but no rows, so return true, but HasRows = false and Read() returns false
          }
        }

        // Ahh, we found a row-returning resultset eligible to be returned!
        _activeStatement = stmt;
        _fieldCount = fieldCount;
        _fieldTypeArray = null;

        return true;
      }
    }

    /// <summary>
    /// Retrieves the SQLiteType for a given column, and caches it to avoid repetetive interop calls.
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>A SQLiteType structure</returns>
    private SQLiteType GetSQLiteType(int i)
    {
      if (_fieldTypeArray == null) _fieldTypeArray = new SQLiteType[_fieldCount];

      if (_fieldTypeArray[i].Affinity == TypeAffinity.Uninitialized || _fieldTypeArray[i].Affinity == TypeAffinity.Null)
        _fieldTypeArray[i].Type = SQLiteConvert.TypeNameToDbType(_activeStatement._sql.ColumnType(_activeStatement, i, out _fieldTypeArray[i].Affinity));
      return _fieldTypeArray[i];
    }

    /// <summary>
    /// Reads the next row from the resultset
    /// </summary>
    /// <returns>True if a new row was successfully loaded and is ready for processing</returns>
    public override bool Read()
    {
      CheckClosed();

      if (_readingState == -1) // First step was already done at the NextResult() level, so don't step again, just return true.
      {
        _readingState = 0;
        return true;
      }
      else if (_readingState == 0) // Actively reading rows
      {
        if (_activeStatement._sql.Step(_activeStatement) == true)
          return true;

        _readingState = 1; // Finished reading rows
      }

      return false;
    }

    /// <summary>
    /// Retrieve the count of records affected by an update/insert command.  Only valid once the data reader is closed!
    /// </summary>
    public override int RecordsAffected
    {
      get { return _rowsAffected; }
    }

    /// <summary>
    /// Indexer to retrieve data from a column given its name
    /// </summary>
    /// <param name="name">The name of the column to retrieve data for</param>
    /// <returns>The value contained in the column</returns>
    public override object this[string name]
    {
      get { return GetValue(GetOrdinal(name)); }
    }

    /// <summary>
    /// Indexer to retrieve data from a column given its i
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>The value contained in the column</returns>
    public override object this[int i]
    {
      get { return GetValue(i); }
    }
  }
}