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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
    object
    NpgsqlCommand
    Implements
    ICloneable
    IComponent
    Namespace: Npgsql
    Assembly: Npgsql.dll
    Syntax
    public class NpgsqlCommand : DbCommand, ICloneable, IComponent

    Constructors

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    NpgsqlCommand()

    Initializes a new instance of the NpgsqlCommand class.

    Declaration
    public NpgsqlCommand()
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    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
    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.

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    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
    string? cmdText

    The text of the query.

    NpgsqlConnection connection

    A NpgsqlConnection that represents the connection to a PostgreSQL server.

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    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
    string? cmdText

    The text of the query.

    Properties

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    AllResultTypesAreUnknown

    Marks all of the query's result columns as either known or unknown. Unknown result columns are requested 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
    bool
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    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 SQL statement or function (stored procedure) to execute. The default is an empty string.

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    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
    int

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

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    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 .

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    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.

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    DbConnection

    DB connection.

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

    DB parameter collection.

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

    DB transaction.

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

    Design time visible.

    Declaration
    public override bool DesignTimeVisible { get; set; }
    Property Value
    Type Description
    bool
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    IsPrepared

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

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

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    Statements

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

    Declaration
    public IReadOnlyList<NpgsqlBatchCommand> Statements { get; }
    Property Value
    Type Description
    IReadOnlyList<><NpgsqlBatchCommand>
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    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 BeginTransaction()

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

    Marks the query's result columns as known or unknown, on a column-by-column basis. Unknown result columns are requested 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
    bool[]
    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.

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    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

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    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.

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    Clone()

    Create a new command based on this one.

    Declaration
    public virtual NpgsqlCommand Clone()
    Returns
    Type Description
    NpgsqlCommand

    A new NpgsqlCommand object.

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    CreateDbParameter()

    Creates a new instance of an object.

    Declaration
    protected override DbParameter CreateDbParameter()
    Returns
    Type Description
    DbParameter

    A object.

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    CreateParameter()

    Creates a new instance of a NpgsqlParameter object.

    Declaration
    public NpgsqlParameter CreateParameter()
    Returns
    Type Description
    NpgsqlParameter

    An NpgsqlParameter object.

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    Dispose(bool)

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

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    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.

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    ExecuteNonQuery()

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

    Declaration
    public override int ExecuteNonQuery()
    Returns
    Type Description
    int

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

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    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<><int>

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

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    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 specifies the command behavior.

    Returns
    Type Description
    NpgsqlDataReader

    A task representing the operation.

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    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.

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    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 specifies 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.

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    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
    object?

    The first column of the first row in the result set, or a null reference if the result set is empty.

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    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<><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.

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    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()
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    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
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    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()
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    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

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    Disposed

    This event is unsupported by Npgsql. Use instead.

    Declaration
    public event EventHandler? Disposed
    Event Type
    Type Description
    EventHandler?

    Implements

    ICloneable
    IComponent
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