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Parameter

The DbManager.Parameter method allows assigning parameters to an SQL query, setting parameter values before query, and getting return/out values after.

Parameter.cs

using System;
using System.Data;

using NUnit.Framework;

using BLToolkit.Data;

namespace HowTo.Data
{
    using DataAccess;

    [TestFixture]
    public class Parameter
    {
        [Test]
        public void AssignParameterTest()
        {
            using (DbManager db = new DbManager())
            {
                int n = db
                    .SetCommand("SELECT @par1 + @par2",
                        db.Parameter("@par1", 2),
                        db.Parameter("@par2", 2))
                    .ExecuteScalar<int>();

                Assert.AreEqual(4, n);
            }
        }

        [Test]
        public void SetValueTest()
        {
            using (DbManager db = new DbManager())
            {
                db.SetCommand("SELECT @par * 2",
                    db.Parameter("@par", DbType.Int32));

                db.Parameter("@par").Value = 2;

                Assert.AreEqual(4, db.ExecuteScalar<int>());
            }
        }

        [Test]
        public void ReturnValueTest()
        {
            using (DbManager db = new DbManager())
            {
                /*
                 * CREATE Function Scalar_ReturnParameter()
                 * RETURNS int
                 * AS
                 * BEGIN
                 *     RETURN 12345
                 * END
                 */
                db
                    .SetSpCommand("Scalar_ReturnParameter")
                    .ExecuteNonQuery();

                int n = (int)db.Parameter("@RETURN_VALUE").Value;

                Assert.AreEqual(12345, n);
            }
        }

        [Test]
        public void ReturnValueTest2()
        {
            using (DbManager db = new DbManager())
            {
                int n = db
                    .SetSpCommand("Scalar_ReturnParameter")
                    .ExecuteScalar<int>(ScalarSourceType.ReturnValue);

                Assert.AreEqual(12345, n);
            }
        }

        [Test]
        public void OutputParameterTest()
        {
            using (DbManager db = new DbManager())
            {
                /*
                 * CREATE Procedure Scalar_OutputParameter
                 *     @outputInt    int         = 0  output,
                 *     @outputString varchar(50) = '' output
                 * AS
                 * BEGIN
                 *     SET @outputInt = 12345
                 *     SET @outputString = '54321'
                 * END
                 */

                db
                    .SetSpCommand("Scalar_OutputParameter",
                        db.OutputParameter("@outputInt",    1),
                        db.OutputParameter("@outputString", "1"))
                    .ExecuteNonQuery();

                Assert.AreEqual(12345,   (int)   db.Parameter("@outputInt").   Value);
                Assert.AreEqual("54321", (string)db.Parameter("@outputString").Value);
            }
        }

        [Test]
        public void OutputParameterAsReturnValueTest()
        {
            using (DbManager db = new DbManager())
            {
                string returnValue = db
                    .SetSpCommand("Scalar_OutputParameter")
                    .ExecuteScalar<string>(ScalarSourceType.OutputParameter, "outputString");

                Assert.AreEqual("54321", returnValue);
            }
        }

        [Test]
        public void CreateParametersTest()
        {
            Person person = new Person();

            person.FirstName = "John";
            person.LastName  = "Smith";
            person.Gender    = Gender.Male;

            using (DbManager db = new DbManager())
            {
                db.BeginTransaction();

                // Prepare command.
                //
                int id = db
                    .SetSpCommand("Person_Insert",
                        db.CreateParameters(person))
                    .ExecuteScalar<int>();

                // Check the result.
                //
                person = db
                    .SetCommand(
                        "SELECT * FROM Person WHERE PersonID = @id",
                        db.Parameter("@id", id))
                    .ExecuteObject<Person>();

                Assert.IsNotNull(person);

                // Cleanup.
                //
                db
                    .SetCommand(
                        "DELETE FROM Person WHERE PersonID = @id",
                        db.Parameter("@id", id))
                    .ExecuteNonQuery();

                db.CommitTransaction();
            }
        }
    }
}

Person.cs

using System;

using BLToolkit.DataAccess;
using BLToolkit.Mapping;

namespace HowTo.DataAccess
{
    public class Person
    {
        [MapField("PersonID"), PrimaryKey, NonUpdatable]
        public int    ID;

        public string LastName;
        public string FirstName;
        public string MiddleName;
        public Gender Gender;
    }
}

Gender.cs

using System;

using BLToolkit.Mapping;

namespace HowTo.DataAccess
{
    public enum Gender
    {
        [MapValue("F")] Female,
        [MapValue("M")] Male,
        [MapValue("U")] Unknown,
        [MapValue("O")] Other
    }
}

App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add
            name             = "DemoConnection"
            connectionString = "Server=.;Database=BLToolkitData;Integrated Security=SSPI"
            providerName     = "System.Data.SqlClient" />
    </connectionStrings>
</configuration>