System.Data.SqlClient.SqlCommand

Overview

The SqlCommand class represents a Transact-SQL statement or stored procedure to execute against a SQL Server database. It provides functionality for executing commands, retrieving results, and managing parameters.

Syntax

public sealed class SqlCommand : DbCommand, ICloneable, IDbCommand, IDbDataParameter, IDataParameter, IDisposable, ICloneable, IAsyncResult

Constructors

Signature	Description
`SqlCommand()`	Initializes a new instance of the SqlCommand class.
`SqlCommand(string cmdText)`	Initializes with the specified command text.
`SqlCommand(string cmdText, SqlConnection connection)`	Initializes with command text and a connection.
`SqlCommand(string cmdText, SqlConnection connection, SqlTransaction transaction)`	Initializes with command text, connection, and transaction.

Properties

Name	Type	Description
`CommandText`	`string`	The Transact-SQL statement or stored procedure to execute.
`CommandType`	`CommandType`	Specifies how the CommandText property is interpreted.
`Connection`	`SqlConnection`	The database connection used by the command.
`Parameters`	`SqlParameterCollection`	Collection of parameters for the command.
`Transaction`	`SqlTransaction`	The transaction within which the command executes.
`Timeout`	`int`	Time (seconds) to wait for command execution.

Methods

Execute methods

Method	Return Type	Description
`ExecuteNonQuery()`	`int`	Executes a command that does not return rows.
`ExecuteReader()`	`SqlDataReader`	Executes the command and returns a data reader.
`ExecuteScalar()`	`object`	Executes the command and returns the first column of the first row.

Asynchronous methods

Method	Return Type	Description
`ExecuteNonQueryAsync(CancellationToken)`	`Task<int>`	Asynchronously executes a command that does not return rows.
`ExecuteReaderAsync(CancellationToken)`	`Task<SqlDataReader>`	Asynchronously executes the command and returns a data reader.
`ExecuteScalarAsync(CancellationToken)`	`Task<object>`	Asynchronously executes the command and returns the first column of the first row.

Miscellaneous methods

Method	Return Type	Description
`Cancel()`	`void`	Cancels the execution of the command.
`CreateParameter()`	`SqlParameter`	Creates a new parameter object.
`Prepare()`	`void`	Prepares the command on the data source.

Examples

Executing a query and reading results

using (SqlConnection conn = new SqlConnection(connectionString))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT Id, Name FROM Products", conn))
    {
        using (SqlDataReader reader = cmd.ExecuteReader())
        {
            while (reader.Read())
            {
                int id = reader.GetInt32(0);
                string name = reader.GetString(1);
                Console.WriteLine($"{id}: {name}");
            }
        }
    }
}

Using parameters with a stored procedure

using (SqlConnection conn = new SqlConnection(connectionString))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand("dbo.GetProductById", conn))
    {
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.Add(new SqlParameter("@ProductId", SqlDbType.Int) { Value = 42 });
        var result = cmd.ExecuteScalar();
        Console.WriteLine($"Product Name: {result}");
    }
}

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