Class DuckDbDataReader

ADO.NET-compatible reader for the results of a query in DuckDB.

Inheritance

object

MarshalByRefObject

DbDataReader

DuckDbDataReader

Implements

IEnumerable

IDataReader

IDataRecord

IDisposable

IAsyncDisposable

Inherited Members

DbDataReader.CloseAsync()

DbDataReader.DisposeAsync()

DbDataReader.GetFieldValueAsync<T>(int)

DbDataReader.GetFieldValueAsync<T>(int, CancellationToken)

DbDataReader.GetSchemaTableAsync(CancellationToken)

DbDataReader.GetColumnSchemaAsync(CancellationToken)

DbDataReader.IsDBNullAsync(int)

DbDataReader.IsDBNullAsync(int, CancellationToken)

DbDataReader.NextResultAsync()

DbDataReader.NextResultAsync(CancellationToken)

DbDataReader.ReadAsync()

DbDataReader.ReadAsync(CancellationToken)

DbDataReader.VisibleFieldCount

MarshalByRefObject.GetLifetimeService()

MarshalByRefObject.InitializeLifetimeService()

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Mallard.Ado

Assembly: Mallard.dll

Syntax

public sealed class DuckDbDataReader : DbDataReader, IEnumerable, IDataReader, IDataRecord, IDisposable, IAsyncDisposable

Properties

Depth

Gets a value indicating the depth of nesting for the current row.

Declaration

public override int Depth { get; }

Property Value

Type	Description
int	The depth of nesting for the current row.

Overrides

DbDataReader.Depth

FieldCount

When overridden in a derived class, gets the number of columns in the current row.

Declaration

public override int FieldCount { get; }

Property Value

Type	Description
int	The number of columns in the current row.

Overrides

DbDataReader.FieldCount

Exceptions

Type	Condition
NotSupportedException	There is no current connection to an instance of SQL Server.

HasRows

When overridden in a derived class, gets a value that indicates whether this DbDataReader contains one or more rows.

Declaration

public override bool HasRows { get; }

Property Value

Type	Description
bool	true if the DbDataReader contains one or more rows; otherwise, false.

Overrides

DbDataReader.HasRows

IsClosed

When overridden in a derived class, gets a value indicating whether the DbDataReader is closed.

Declaration

public override bool IsClosed { get; }

Property Value

Type	Description
bool	true if the DbDataReader is closed; otherwise, false.

Overrides

DbDataReader.IsClosed

Exceptions

Type	Condition
InvalidOperationException	The DbDataReader is closed.

this[int]

When overridden in a derived class, gets the value of the specified column as an instance of object.

Declaration

public override object this[int ordinal] { get; }

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Property Value

Type	Description
object	The value of the specified column.

Overrides

DbDataReader.this[int]

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.

this[string]

When overridden in a derived class, gets the value of the specified column as an instance of object.

Declaration

public override object this[string name] { get; }

Parameters

Type	Name	Description
string	name	The name of the column.

Property Value

Type	Description
object	The value of the specified column.

Overrides

DbDataReader.this[string]

Exceptions

Type	Condition
IndexOutOfRangeException	No column with the specified name was found.

RecordsAffected

When overridden in a derived class, gets the number of rows changed, inserted, or deleted by execution of the SQL statement.

Declaration

public override int RecordsAffected { get; }

Property Value

Type	Description
int	The number of rows changed, inserted, or deleted. -1 for SELECT statements; 0 if no rows were affected or the statement failed.

Overrides

DbDataReader.RecordsAffected

Methods

Close()

Closes the DbDataReader object.

Declaration

public override void Close()

Overrides

DbDataReader.Close()

GetBoolean(int)

When overridden in a derived class, gets the value of the specified column as a Boolean.

Declaration

public override bool GetBoolean(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
bool	The value of the specified column.

Overrides

DbDataReader.GetBoolean(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetByte(int)

When overridden in a derived class, gets the value of the specified column as a byte.

Declaration

public override byte GetByte(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
byte	The value of the specified column.

Overrides

DbDataReader.GetByte(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetBytes(int, long, byte[]?, int, int)

When overridden in a derived class, reads a specified number of bytes from the specified column starting at a specified index and writes them to a buffer starting at a specified position in the buffer.

Declaration

public override long GetBytes(int ordinal, long dataOffset, byte[]? buffer, int bufferOffset, int length)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.
long	dataOffset	The index within the row from which to begin the read operation.
byte[]	buffer	The buffer into which to copy the data.
int	bufferOffset	The index with the buffer to which the data will be copied.
int	length	The maximum number of bytes to read.

Returns

Type	Description
long	The actual number of bytes read.

Overrides

DbDataReader.GetBytes(int, long, byte[], int, int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetChar(int)

When overridden in a derived class, gets the value of the specified column as a single character.

Declaration

public override char GetChar(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
char	The value of the specified column.

Overrides

DbDataReader.GetChar(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetChars(int, long, char[]?, int, int)

When overridden in a derived class, reads a specified number of characters from a specified column starting at a specified index, and writes them to a buffer starting at a specified position.

Declaration

public override long GetChars(int ordinal, long dataOffset, char[]? buffer, int bufferOffset, int length)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.
long	dataOffset	The index within the row from which to begin the read operation.
char[]	buffer	The buffer into which to copy the data.
int	bufferOffset	The index with the buffer to which the data will be copied.
int	length	The maximum number of characters to read.

Returns

Type	Description
long	The actual number of characters read.

Overrides

DbDataReader.GetChars(int, long, char[], int, int)

GetDataTypeName(int)

When overridden in a derived class, gets name of the data type of the specified column.

Declaration

public override string GetDataTypeName(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
string	The name of the data type.

Overrides

DbDataReader.GetDataTypeName(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.

GetDateTime(int)

When overridden in a derived class, gets the value of the specified column as a DateTime object.

Declaration

public override DateTime GetDateTime(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
DateTime	The value of the specified column.

Overrides

DbDataReader.GetDateTime(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetDecimal(int)

When overridden in a derived class, gets the value of the specified column as a decimal.

Declaration

public override decimal GetDecimal(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
decimal	The value of the specified column.

Overrides

DbDataReader.GetDecimal(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetDouble(int)

When overridden in a derived class, gets the value of the specified column as a double-precision floating point number.

Declaration

public override double GetDouble(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
double	The value of the specified column.

Overrides

DbDataReader.GetDouble(int)

Exceptions

Type	Condition
InvalidCastException	The specified cast is not valid.

GetEnumerator()

When overridden in a derived class, returns an enumerator that can be used to iterate through the rows in the data reader.

Declaration

public override IEnumerator GetEnumerator()

Returns

Type	Description
IEnumerator	An enumerator that can be used to iterate through the rows in the data reader.

Overrides

System.Data.Common.DbDataReader.GetEnumerator()

GetFieldType(int)

When overridden in a derived class, gets the data type of the specified column.

Declaration

public override Type GetFieldType(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
Type	The data type of the specified column.

Overrides

DbDataReader.GetFieldType(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetFieldValue<T>(int)

Gets the value of the specified column as the requested type.

Declaration

public override T GetFieldValue<T>(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
T	The value of the specified column.

Type Parameters

Name	Description
T	The type of the value to be returned.

Overrides

DbDataReader.GetFieldValue<T>(int)

Exceptions

Type	Condition
InvalidOperationException	The connection was dropped or closed during data retrieval. -or- The data reader was closed during data retrieval. -or- There is no data ready to be read (for example, the first Read() hasn't been called, or it returned false). -or- The reader tried to read a previously-read column in sequential mode. -or- There was an asynchronous operation in progress. This applies to all Get* methods when running in sequential mode, as they could be called while reading a stream.
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The value returned by the database doesn't match or cannot be cast to T.

GetFloat(int)

When overridden in a derived class, gets the value of the specified column as a single-precision floating point number.

Declaration

public override float GetFloat(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
float	The value of the specified column.

Overrides

DbDataReader.GetFloat(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetGuid(int)

When overridden in a derived class, gets the value of the specified column as a globally unique identifier (GUID).

Declaration

public override Guid GetGuid(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
Guid	The value of the specified column.

Overrides

DbDataReader.GetGuid(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetInt16(int)

When overridden in a derived class, gets the value of the specified column as a 16-bit signed integer.

Declaration

public override short GetInt16(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
short	The value of the specified column.

Overrides

DbDataReader.GetInt16(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetInt32(int)

When overridden in a derived class, gets the value of the specified column as a 32-bit signed integer.

Declaration

public override int GetInt32(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
int	The value of the specified column.

Overrides

DbDataReader.GetInt32(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetInt64(int)

When overridden in a derived class, gets the value of the specified column as a 64-bit signed integer.

Declaration

public override long GetInt64(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
long	The value of the specified column.

Overrides

DbDataReader.GetInt64(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetName(int)

When overridden in a derived class, gets the name of the column, given the zero-based column ordinal.

Declaration

public override string GetName(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
string	The name of the specified column.

Overrides

DbDataReader.GetName(int)

GetOrdinal(string)

When overridden in a derived class, gets the column ordinal given the name of the column.

Declaration

public override int GetOrdinal(string name)

Parameters

Type	Name	Description
string	name	The name of the column.

Returns

Type	Description
int	The zero-based column ordinal.

Overrides

DbDataReader.GetOrdinal(string)

Exceptions

Type	Condition
IndexOutOfRangeException	The name specified is not a valid column name.

GetSchemaTable()

Returns a DataTable that describes the result columns.

Declaration

public override DataTable GetSchemaTable()

Returns

Type	Description
DataTable	A DataTable with the columns:

Overrides

DbDataReader.GetSchemaTable()

Remarks

Implementations of this method in other ADO.NET providers re-query the database to obtain detailed information on the columns such as key constraints. Doing the same is difficult in DuckDB's C API, so this implementation provides basic information only.

The returned instance is created anew by this method and is not cached.

GetStream(int)

Gets a stream to retrieve data from the specified column.

Declaration

public override Stream GetStream(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
Stream	A stream.

Overrides

DbDataReader.GetStream(int)

Exceptions

Type	Condition
InvalidOperationException	The connection was dropped or closed during the data retrieval. -or- The data reader is closed during the data retrieval. -or- There is no data ready to be read (for example, the first Read() hasn't been called, or returned false). -or- The data reader tried to read a previously-read column in sequential mode. -or- There was an asynchronous operation in progress. This applies to all Get* methods when running in sequential mode, as they could be called while reading a stream.
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified column isn't a binary type that supports reading with a Stream.

GetString(int)

When overridden in a derived class, gets the value of the specified column as an instance of string.

Declaration

public override string GetString(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
string	The value of the specified column.

Overrides

DbDataReader.GetString(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified cast is not valid.

GetTextReader(int)

Gets a text reader to retrieve data from the column.

Declaration

public override TextReader GetTextReader(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
TextReader	A text reader.

Overrides

DbDataReader.GetTextReader(int)

Exceptions

Type	Condition
InvalidOperationException	The connection was dropped or closed during the data retrieval. -or- The data reader is closed during the data retrieval. -or- There is no data ready to be read (for example, the first Read() hasn't been called, or returned false). -or- The data reader tried to read a previously-read column in sequential mode. -or- There was an asynchronous operation in progress. This applies to all Get* methods when running in sequential mode, as they could be called while reading a stream.
IndexOutOfRangeException	The column index is out of range.
InvalidCastException	The specified column isn't a text type that supports reading with a TextReader.

GetValue(int)

When overridden in a derived class, gets the value of the specified column as an instance of object.

Declaration

public override object GetValue(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
object	The value of the specified column.

Overrides

DbDataReader.GetValue(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.

GetValues(object[])

When overridden in a derived class, populates an array of objects with the column values of the current row.

Declaration

public override int GetValues(object[] values)

Parameters

Type	Name	Description
object[]	values	An array of object into which to copy the attribute columns.

Returns

Type	Description
int	The number of instances of object in the array.

Overrides

DbDataReader.GetValues(object[])

IsDBNull(int)

When overridden in a derived class, gets a value that indicates whether the column contains nonexistent or missing values.

Declaration

public override bool IsDBNull(int ordinal)

Parameters

Type	Name	Description
int	ordinal	The zero-based column ordinal.

Returns

Type	Description
bool	true if the specified column is equivalent to DBNull; otherwise, false.

Overrides

DbDataReader.IsDBNull(int)

Exceptions

Type	Condition
IndexOutOfRangeException	The column index is out of range.

NextResult()

When overridden in a derived class, advances the reader to the next result when reading the results of a batch of statements.

Declaration

public override bool NextResult()

Returns

Type	Description
bool	true if there are more result sets; otherwise, false.

Overrides

DbDataReader.NextResult()

Read()

When overridden in a derived class, advances the reader to the next record in a result set.

Declaration

public override bool Read()

Returns

Type	Description
bool	true if there are more rows; otherwise, false.

Overrides

DbDataReader.Read()

Implements

IEnumerable

IDataReader

IDataRecord

IDisposable

IAsyncDisposable