Class NpgsqlCommand

Represents a SQL statement or function (stored procedure) to execute against a PostgreSQL database. This class cannot be inherited.

Inheritance

Object

NpgsqlCommand

Implements

ICloneable

IComponent

Namespace: Npgsql

Assembly: Npgsql.dll

Syntax

public sealed class NpgsqlCommand : DbCommand, ICloneable, IComponent

Constructors

NpgsqlCommand()

Initializes a new instance of the NpgsqlCommand class.

Declaration

public NpgsqlCommand()

NpgsqlCommand(Nullable<String>)

Initializes a new instance of the NpgsqlCommand class with the text of the query.

Declaration

public NpgsqlCommand(string? cmdText)

Parameters

Type	Name	Description
Nullable<String>	cmdText	The text of the query.

NpgsqlCommand(Nullable<String>, NpgsqlConnection)

Initializes a new instance of the NpgsqlCommand class with the text of the query and a NpgsqlConnection.

Declaration

public NpgsqlCommand(string? cmdText, NpgsqlConnection connection)

Parameters

Type	Name	Description
Nullable<String>	cmdText	The text of the query.
NpgsqlConnection	connection	A NpgsqlConnection that represents the connection to a PostgreSQL server.

NpgsqlCommand(Nullable<String>, NpgsqlConnection, NpgsqlTransaction)

Initializes a new instance of the NpgsqlCommand class with the text of the query, a NpgsqlConnection, and the NpgsqlTransaction.

Declaration

public NpgsqlCommand(string? cmdText, NpgsqlConnection connection, NpgsqlTransaction transaction)

Parameters

Type	Name	Description
Nullable<String>	cmdText	The text of the query.
NpgsqlConnection	connection	A NpgsqlConnection that represents the connection to a PostgreSQL server.
NpgsqlTransaction	transaction	The NpgsqlTransaction in which the NpgsqlCommand executes.

Properties

AllResultTypesAreUnknown

Marks all of the query's result columns as either known or unknown. Unknown results column are requested them from PostgreSQL in text format, and Npgsql makes no attempt to parse them. They will be accessible as strings only.

Declaration

public bool AllResultTypesAreUnknown { get; set; }

Property Value

Type	Description
Boolean

CommandText

Gets or sets the SQL statement or function (stored procedure) to execute at the data source.

Declaration

public override string CommandText { get; set; }

Property Value

Type	Description
String	The Transact-SQL statement or stored procedure to execute. The default is an empty string.

CommandTimeout

Gets or sets the wait time (in seconds) before terminating the attempt to execute a command and generating an error.

Declaration

public override int CommandTimeout { get; set; }

Property Value

Type	Description
Int32	The time (in seconds) to wait for the command to execute. The default value is 30 seconds.

CommandType

Gets or sets a value indicating how the CommandText property is to be interpreted.

Declaration

public override CommandType CommandType { get; set; }

Property Value

Type	Description
CommandType	One of the values. The default is .

Connection

Gets or sets the NpgsqlConnection used by this instance of the NpgsqlCommand.

Declaration

public NpgsqlConnection Connection { get; set; }

Property Value

Type	Description
NpgsqlConnection	The connection to a data source. The default value is null.

DbConnection

DB connection.

Declaration

protected override DbConnection? DbConnection { get; set; }

Property Value

Type	Description
Nullable<DbConnection>

DbParameterCollection

DB parameter collection.

Declaration

protected override DbParameterCollection DbParameterCollection { get; }

Property Value

Type	Description
DbParameterCollection

DbTransaction

DB transaction.

Declaration

protected override DbTransaction? DbTransaction { get; set; }

Property Value

Type	Description
Nullable<DbTransaction>

DesignTimeVisible

Design time visible.

Declaration

public override bool DesignTimeVisible { get; set; }

Property Value

Type	Description
Boolean

IsPrepared

Returns whether this query will execute as a prepared (compiled) query.

Declaration

public bool IsPrepared { get; }

Property Value

Type	Description
Boolean

Parameters

Gets the NpgsqlParameterCollection.

Declaration

public NpgsqlParameterCollection Parameters { get; }

Property Value

Type	Description
NpgsqlParameterCollection	The parameters of the SQL statement or function (stored procedure). The default is an empty collection.

Statements

Returns details about each statement that this command has executed. Is only populated when an Execute* method is called.

Declaration

public IReadOnlyList<NpgsqlStatement> Statements { get; }

Property Value

Type	Description
IReadOnlyList<NpgsqlStatement>

Transaction

This property is ignored by Npgsql. PostgreSQL only supports a single transaction at a given time on a given connection, and all commands implicitly run inside the current transaction started via

Declaration

public NpgsqlTransaction Transaction { get; set; }

Property Value

Type	Description
NpgsqlTransaction

UnknownResultTypeList

Marks the query's result columns as known or unknown, on a column-by-column basis. Unknown results column are requested them from PostgreSQL in text format, and Npgsql makes no attempt to parse them. They will be accessible as strings only.

Declaration

public bool[] UnknownResultTypeList { get; set; }

Property Value

Type	Description
Boolean[]

Remarks

If the query includes several queries (e.g. SELECT 1; SELECT 2), this will only apply to the first one. The rest of the queries will be fetched and parsed as usual.

The array size must correspond exactly to the number of result columns the query returns, or an error will be raised.

UpdatedRowSource

Gets or sets how command results are applied to the DataRow when used by the DbDataAdapter.Update(DataSet) method.

Declaration

public override UpdateRowSource UpdatedRowSource { get; set; }

Property Value

Type	Description
UpdateRowSource	One of the values.

Methods

Cancel()

Attempts to cancel the execution of an NpgsqlCommand.

Declaration

public override void Cancel()

Remarks

As per the specs, no exception will be thrown by this method in case of failure.

Clone()

Create a new command based on this one.

Declaration

public NpgsqlCommand Clone()

Returns

Type	Description
NpgsqlCommand	A new NpgsqlCommand object.

CreateDbParameter()

Creates a new instance of an object.

Declaration

protected override DbParameter CreateDbParameter()

Returns

Type	Description
DbParameter	A object.

CreateParameter()

Creates a new instance of a NpgsqlParameter object.

Declaration

public NpgsqlParameter CreateParameter()

Returns

Type	Description
NpgsqlParameter	An NpgsqlParameter object.

Dispose(Boolean)

Releases the resources used by the NpgsqlCommand.

Declaration

protected override void Dispose(bool disposing)

Parameters

Type	Name	Description
Boolean	disposing

ExecuteDbDataReader(CommandBehavior)

Executes the command text against the connection.

Declaration

protected override DbDataReader ExecuteDbDataReader(CommandBehavior behavior)

Parameters

Type	Name	Description
CommandBehavior	behavior

Returns

Type	Description
DbDataReader	A task representing the operation.

ExecuteDbDataReaderAsync(CommandBehavior, CancellationToken)

Executes the command text against the connection.

Declaration

protected override Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken)

Parameters

Type	Name	Description
CommandBehavior	behavior	An instance of .
CancellationToken	cancellationToken	An optional token to cancel the asynchronous operation. The default value is .

Returns

Type	Description
Task<DbDataReader>	A task representing the asynchronous operation.

ExecuteNonQuery()

Executes a SQL statement against the connection and returns the number of rows affected.

Declaration

public override int ExecuteNonQuery()

Returns

Type	Description
Int32	The number of rows affected if known; -1 otherwise.

ExecuteNonQueryAsync(CancellationToken)

Asynchronous version of ExecuteNonQuery()

Declaration

public override Task<int> ExecuteNonQueryAsync(CancellationToken cancellationToken)

Parameters

Type	Name	Description
CancellationToken	cancellationToken	An optional token to cancel the asynchronous operation. The default value is .

Returns

Type	Description
Task<Int32>	A task representing the asynchronous operation, with the number of rows affected if known; -1 otherwise.

ExecuteReader(CommandBehavior)

Executes the CommandText against the Connection and returns a NpgsqlDataReader.

Declaration

public NpgsqlDataReader ExecuteReader(CommandBehavior behavior = null)

Parameters

Type	Name	Description
CommandBehavior	behavior	One of the enumeration values that specified the command behavior.

Returns

Type	Description
NpgsqlDataReader	A task representing the operation.

ExecuteReaderAsync(CancellationToken)

An asynchronous version of ExecuteReader(CommandBehavior), which executes the CommandText against the Connection and returns a NpgsqlDataReader.

Declaration

public Task<NpgsqlDataReader> ExecuteReaderAsync(CancellationToken cancellationToken = null)

Parameters

Type	Name	Description
CancellationToken	cancellationToken	An optional token to cancel the asynchronous operation. The default value is .

Returns

Type	Description
Task<NpgsqlDataReader>	A task representing the asynchronous operation.

ExecuteReaderAsync(CommandBehavior, CancellationToken)

An asynchronous version of ExecuteReader(CommandBehavior), which executes the CommandText against the Connection and returns a NpgsqlDataReader.

Declaration

public Task<NpgsqlDataReader> ExecuteReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken = null)

Parameters

Type	Name	Description
CommandBehavior	behavior	One of the enumeration values that specified the command behavior.
CancellationToken	cancellationToken	An optional token to cancel the asynchronous operation. The default value is .

Returns

Type	Description
Task<NpgsqlDataReader>	A task representing the asynchronous operation.

ExecuteScalar()

Executes the query, and returns the first column of the first row in the result set returned by the query. Extra columns or rows are ignored.

Declaration

public override object? ExecuteScalar()

Returns

Type	Description
Nullable<Object>	The first column of the first row in the result set, or a null reference if the result set is empty.

ExecuteScalarAsync(CancellationToken)

Asynchronous version of ExecuteScalar()

Declaration

public override Task<object?> ExecuteScalarAsync(CancellationToken cancellationToken)

Parameters

Type	Name	Description
CancellationToken	cancellationToken	An optional token to cancel the asynchronous operation. The default value is .

Returns

Type	Description
Task<Nullable<Object>>	A task representing the asynchronous operation, with the first column of the first row in the result set, or a null reference if the result set is empty.

Prepare()

Creates a server-side prepared statement on the PostgreSQL server. This will make repeated future executions of this command much faster.

Declaration

public override void Prepare()

PrepareAsync(CancellationToken)

Creates a server-side prepared statement on the PostgreSQL server. This will make repeated future executions of this command much faster.

Declaration

public override Task PrepareAsync(CancellationToken cancellationToken = null)

Parameters

Type	Name	Description
CancellationToken	cancellationToken	An optional token to cancel the asynchronous operation. The default value is .

Returns

Type	Description
Task

Unprepare()

Unprepares a command, closing server-side statements associated with it. Note that this only affects commands explicitly prepared with Prepare(), not automatically prepared statements.

Declaration

public void Unprepare()

UnprepareAsync(CancellationToken)

Unprepares a command, closing server-side statements associated with it. Note that this only affects commands explicitly prepared with Prepare(), not automatically prepared statements.

Declaration

public Task UnprepareAsync(CancellationToken cancellationToken = null)

Parameters

Type	Name	Description
CancellationToken	cancellationToken	An optional token to cancel the asynchronous operation. The default value is .

Returns

Type	Description
Task

Events

Disposed

This event is unsupported by Npgsql. Use instead.

Declaration

public event EventHandler? Disposed

Event Type

Type	Description
Nullable<EventHandler>

Implements

ICloneable

IComponent