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Class NpgsqlCommand

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

Inheritance
System.Object
NpgsqlCommand
Implements
ICloneable
Namespace: Npgsql
Assembly: Npgsql.dll
Syntax
public sealed class NpgsqlCommand : DbCommand, ICloneable

Constructors

NpgsqlCommand()

Initializes a new instance of the NpgsqlCommand class.

Declaration
public NpgsqlCommand()

NpgsqlCommand(String)

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

Declaration
public NpgsqlCommand(string cmdText)
Parameters
Type Name Description
System.String cmdText

The text of the query.

NpgsqlCommand(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
System.String cmdText

The text of the query.

NpgsqlConnection connection

A NpgsqlConnection that represents the connection to a PostgreSQL server.

NpgsqlCommand(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
System.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
System.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
System.String

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

CommandTimeout

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

Declaration
public override int CommandTimeout { get; set; }
Property Value
Type Description
System.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 CommandType values. The default is CommandType.Text.

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 a null reference.

DbConnection

DB connection.

Declaration
protected override DbConnection DbConnection { get; set; }
Property Value
Type Description
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
DbTransaction

DesignTimeVisible

Design time visible.

Declaration
public override bool DesignTimeVisible { get; set; }
Property Value
Type Description
System.Boolean

IsPrepared

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

Declaration
public bool IsPrepared { get; }
Property Value
Type Description
System.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

Gets or sets the NpgsqlTransaction within which the NpgsqlCommand executes.

Declaration
public NpgsqlTransaction Transaction { get; set; }
Property Value
Type Description
NpgsqlTransaction

The NpgsqlTransaction. The default value is a null reference.

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
System.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 UpdateRowSource values.

Methods

Cancel()

Attempts to cancel the execution of a 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 DbParameter object.

Declaration
protected override DbParameter CreateDbParameter()
Returns
Type Description
DbParameter

An DbParameter object.

CreateParameter()

Creates a new instance of a NpgsqlParameter object.

Declaration
public NpgsqlParameter CreateParameter()
Returns
Type Description
NpgsqlParameter

A NpgsqlParameter object.

Dispose(Boolean)

Releases the resources used by the NpgsqlCommand.

Declaration
protected override void Dispose(bool disposing)
Parameters
Type Name Description
System.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

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

A task representing the operation.

Returns
Type Description
Task<DbDataReader>

ExecuteNonQuery()

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

Declaration
public override int ExecuteNonQuery()
Returns
Type Description
System.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

The token to monitor for cancellation requests.

Returns
Type Description
Task<System.Int32>

A task representing the asynchronous operation, with the number of rows affected if known; -1 otherwise.

ExecuteReader()

Executes the CommandText against the Connection, and returns an DbDataReader.

Declaration
public NpgsqlDataReader ExecuteReader()
Returns
Type Description
NpgsqlDataReader

A DbDataReader object.

Remarks

Unlike the ADO.NET method which it replaces, this method returns a Npgsql-specific DataReader.

ExecuteReader(CommandBehavior)

Executes the CommandText against the Connection, and returns an DbDataReader using one of the CommandBehavior values.

Declaration
public NpgsqlDataReader ExecuteReader(CommandBehavior behavior)
Parameters
Type Name Description
CommandBehavior behavior
Returns
Type Description
NpgsqlDataReader

A DbDataReader object.

Remarks

Unlike the ADO.NET method which it replaces, this method returns a Npgsql-specific DataReader.

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
System.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

The token to monitor for cancellation requests.

Returns
Type Description
Task<System.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 prepared version of the command on a PostgreSQL server.

Declaration
public override void Prepare()

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()

Implements

ICloneable
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