Query Class

Represents a database query.

Inheritance Hierarchy

System.Object
  Microsoft.Web.Management.DatabaseManager.Query

Namespace:  Microsoft.Web.Management.DatabaseManager
Assembly:  Microsoft.Web.Management.DatabaseManager (in Microsoft.Web.Management.DatabaseManager.dll)

Syntax

'Declaration
Public Class Query
'Usage
Dim instance As Query

public class Query

public ref class Query

public class Query

The Query type exposes the following members.

Constructors

	Name	Description
	Query	Creates a new instance of the Query class.

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Properties

	Name	Description
	AllowEdit	Gets or sets a value that specifies whether editing the query is allowed.
	Statement	Gets or sets the SQL statement for a query.
	Tag	Returns a generic object that is stored in the Query class.

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Methods

	Name	Description
	Equals	(Inherited from Object.)
	Finalize	(Inherited from Object.)
	GetHashCode	(Inherited from Object.)
	GetType	(Inherited from Object.)
	MemberwiseClone	(Inherited from Object.)
	ToString	(Inherited from Object.)

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Remarks

The Query class represents a query as an object for working with a database. In the most basic implementation, a query would consist of a SQL statement that is contained in the Statement property.

Examples

The following code sample illustrates an example ExecuteQuery method that returns an array of query results from a database query.

    Public Overrides Function ExecuteQuery( _
            ByVal connectionString As String, _
            ByVal query As Microsoft.Web.Management.DatabaseManager.Query) _
            As Microsoft.Web.Management.DatabaseManager.QueryResult()

        Dim results As List(Of QueryResult) = New List(Of QueryResult)
        Dim result As QueryResult = New QueryResult
        Try
            ' Create a new OLEDB connection using the connection string.
            Dim connection As OleDbConnection = New OleDbConnection(connectionString)
            Dim command As OleDbCommand = New OleDbCommand(query.Statement, connection)
            ' Open the database connection.
            connection.Open()
            ' Execute the query and access the data.
            Dim reader As OleDbDataReader = command.ExecuteReader
            ' Add the results to the query list.
            results.Add(GetQueryResult(reader))
            ' Close the database connection.
            reader.Close()
            ' Return the query results.
            Return results.ToArray
        Catch ex As Exception
            Throw New ProviderException(ex.Message)
        End Try

    End Function



...



    Private Function GetQueryResult(ByVal reader As OleDbDataReader) As QueryResult
        Dim result As QueryResult = New QueryResult
        Dim fieldCount As Integer = reader.FieldCount
        Dim i As Integer = 0
        Do While (i < fieldCount)
            Dim metadata As QueryColumnMetadata = New QueryColumnMetadata
            metadata.Name = reader.GetName(i)
            result.ColumnMetadata.Add(metadata)
            i = (i + 1)
        Loop

        While reader.Read
            Dim itemData() As Object = New Object((fieldCount) - 1) {}
            i = 0
            Do While (i < fieldCount)
                itemData(i) = ConvertToSerializable(reader(i))
                i = (i + 1)
            Loop
            result.QueryResults.Add(itemData)

        End While
        Return result
    End Function

        public override QueryResult[] ExecuteQuery(
            string connectionString,
            Query query )
        {
            List<QueryResult> results = new List<QueryResult>();
            QueryResult result = new QueryResult();
            try
            {
                // Create a new OLEDB connection using the connection string.
                using (OleDbConnection connection = new OleDbConnection(connectionString))
                {
                    OleDbCommand command = new OleDbCommand(query.Statement, connection);
                    // Open the database connection.
                    connection.Open();
                    // Execute the query and access the data.
                    OleDbDataReader reader = command.ExecuteReader();
                    // Add the results to the query list.
                    results.Add(GetQueryResult(reader));
                    // Close the database connection.
                    reader.Close();
                }
                // Return the query results.
                return results.ToArray();
            }
            catch(Exception ex)
            {
                throw new ProviderException(ex.Message);
            }
        }



...



        private QueryResult GetQueryResult(OleDbDataReader reader)
        {
            QueryResult result = new QueryResult();
            int fieldCount = reader.FieldCount;

            for (int i = 0; i < fieldCount; i++)
            {
                QueryColumnMetadata metadata = new QueryColumnMetadata();
                metadata.Name = reader.GetName(i);
                result.ColumnMetadata.Add(metadata);
            }

            while (reader.Read())
            {
                object[] itemData = new object[fieldCount];
                for (int i = 0; i < fieldCount; i++)
                {
                    itemData[i] = ConvertToSerializable(reader[i]);
                }
                result.QueryResults.Add(itemData);
            }
            return result;
        }

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also

Reference

Microsoft.Web.Management.DatabaseManager Namespace