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ExecuteQuery


This method is used to execute a raw-SQL directly towards the database. It returns an IEnumerable<T> object. This method supports all types of RDMBS data providers.

Code Snippets

Below is a code that query all the rows from the [dbo].[Person] table from the database.

using (var connection = new SqlConnection(connectionString))
{
    var people = connection.ExecuteQuery<Person>("SELECT * FROM [dbo].[Person];");
}

Returning the enumerable of dynamic objects. The type of the dynamic object is an ExpandoObject.

using (var connection = new SqlConnection(connectionString))
{
    var dynamicPeople = connection.ExecuteQuery("SELECT * FROM [dbo].[Person];");
}

Returning the enumerable of ExpandoObject objects.

using (var connection = new SqlConnection(connectionString))
{
    var people = connection.ExecuteQuery<ExpandoObject>("SELECT * FROM [dbo].[Person];");
}

Returning the enumerable of IDictionary<string, object> objects.

using (var connection = new SqlConnection(connectionString))
{
    var people = connection.ExecuteQuery<IDictionary<string, object>>("SELECT * FROM [dbo].[Person];");
}

Note: You can as well pass an anonymous type in the generic type TResult of the ExecuteQuery operation. This scenario is very important to the F# programming language.

Typed Result

You can also infer the result back to any .NET CLR Type. Below is for long type.

using (var connection = new SqlConnection(connectionString))
{
    var ids = connection.ExecuteQuery<long>("SELECT Id FROM [dbo].[Person];");
}

Or for the other types like string and DateTime.

using (var connection = new SqlConnection(connectionString))
{
    var names = connection.ExecuteQuery<string>("SELECT Name FROM [dbo].[Person];");
    var dateOfBirth = connection.ExecuteQuery<DateTime>("SELECT DateOfBirth FROM [dbo].[Person] WHERE Name = 'John Doe';").FirstOrDefault();
}

And also for the Enum types.

// Enumeration
public enum Gender
{
    Male = 1,
    Female = 2
}

// Inferring
using (var connection = new SqlConnection(connectionString))
{
    var gender = connection.ExecuteQuery<Gender>("SELECT Gender FROM [dbo].[Person] WHERE Name = 'John Doe';").FirstOrDefault();
}

Note: The inferrence of the enumeration will work for string types (i.e: NVARCHAR, TEXT, etc) and non-string types (i.e: SMALLINT, INT, BIGINT, etc) column types.

Table-Valued Parameters

To execute a Table-Valued Parameter (TVP), create a DataTable and set its name equals to the name of the User-Defined Type (UDT).

Please click here to follow the Microsoft guidelines on how to create a TVP and UDT and call it from C#/ADO.NET.

var table = new DataTable();
table.TableName = "Name of the UDT";
// Create the 'table' columns/rows

Then, pass it as a value to your argument.

using (var connection = new SqlConnection(connectionString))
{
    var tables = connection.ExecuteQuery<IdentityTable>("EXEC [sp_StoredProcedureName] @Table = @Table;",
        new { Table = table })?.AsList();
}

Passing of Parameters

You can pass a parameter via the following objects.

  • Anonymous Types
  • ExpandoObject
  • IDictionary<string, object>
  • QueryField/QueryGroup

Please see the sample code snippets below.

Anonymous Types

using (var connection = new SqlConnection(connectionString))
{
    var param = new
    {
        Id = 10045
    };
    var person = connection.ExecuteQuery<Person>("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param).FirstOrDefault();
}

ExpandoObject

using (var connection = new SqlConnection(connectionString))
{
    var param = new ExpandoObject() as IDictionary<string, object>;
    param.Add("Id", 10045);
    var person = connection.ExecuteQuery<Person>("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param).FirstOrDefault();
}

IDictionary<string, object>

using (var connection = new SqlConnection(connectionString))
{
    var param = new Dictionary<string, object>
    {
        { "Id", 10045 }
    };
    var person = connection.ExecuteQuery<Person>("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param).FirstOrDefault();
}

QueryField/QueryGroup

using (var connection = new SqlConnection(connectionString))
{
    var param = new []
    {
        new QueryField("Id", 10045)
    };
    var person = connection.ExecuteQuery<Person>("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param).FirstOrDefault();
}

Or via QueryGroup.

using (var connection = new SqlConnection(connectionString))
{
    var param = new QueryGroup(new []
    {
        new QueryField("Id", 10045)
    });
    var person = connection.ExecuteQuery<Person>("SELECT * FROM [dbo].[Person] WHERE Id = @Id;", param).FirstOrDefault();
}

Array Parameters (for the IN keyword)

You can pass an array of values if you are using the IN keyword.

using (var connection = new SqlConnection(connectionString))
{
    var param = new
    {
        Keys = new [] { 10045, 10102, 11004 }
    };
    var people = connection.ExecuteQuery<Person>("SELECT * FROM dbo].[Person] WHERE Id IN (@Keys);", param);
}

You can also use the types defined at the Passing of Parameters section when passing a parameter.

Executing a StoredProcedure

There are 2 ways of executing a stored procedure. First, simply pass the name of the stored procedure and set the command type to CommandType.StoredProcedure.

using (var connection = new SqlConnection(connectionString))
{
    var person = connection.ExecuteQuery<Person>("[dbo].[sp_GetPerson]",
        new { Id = 10045 }, commandType: CommandType.StoredProcedure).FirstOrDefault();
}

Or, simply use the native SQL calls like below.

using (var connection = new SqlConnection(connectionString))
{
    var person = connection.ExecuteQuery<Person>("EXEC [dbo].[sp_GetPerson](@Id);",
        new { Id = 10045 }).FirstOrDefault();
}

Notice in the second call, there is semi-colon at the end of the command text and the command type was not set.