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Dapper.NET : Executing Commands


Curious Bot - December 1, 2018 - 0 comments

Execute a command that returns no results

IDBConnection db = /* ... */
var id = /* ... */

db.Execute(@"update dbo.Dogs set Name = 'Beowoof' where Id = @id",
new { id });

Stored Procedures

Simple usage

Dapper fully supports stored procs:

var user = conn.Query<User>("spGetUser", new { Id = 1 },
commandType: CommandType.StoredProcedure)
.SingleOrDefault();

Input, Output and Return parameters

If you want something more fancy, you can do:

var p = new DynamicParameters();
p.Add("@a", 11);
p.Add("@b",
dbType: DbType.Int32,
direction: ParameterDirection.Output);
p.Add("@c",
dbType: DbType.Int32,
direction: ParameterDirection.ReturnValue);

conn.Execute("spMagicProc", p,
commandType: CommandType.StoredProcedure);

var b = p.Get<int>("@b");
var c = p.Get<int>("@c");

Table Valued Parameters

If you have a stored procedure that accepts a Table Valued Parameter, you need to pass a DataTable which has the same structure as the table type in SQL Server has.
Here’s a definition for a table type and procedure utilizing it:

CREATE TYPE [dbo].[myUDTT] AS TABLE([i1] [int] NOT NULL);
GO
CREATE PROCEDURE myProc(@data dbo.myUDTT readonly) AS
SELECT i1 FROM @data;
GO
/*
-- optionally grant permissions as needed, depending on the user you execute this with.
-- Especially the GRANT EXECUTE ON TYPE is often overlooked and can cause problems if omitted.
GRANT EXECUTE ON TYPE::[dbo].[myUDTT] TO [user];
GRANT EXECUTE ON dbo.myProc TO [user];
GO
*/

To call that procedure from within c#, you need to do the following:

// Build a DataTable with one int column
DataTable data = new DataTable();
data.Columns.Add("i1", typeof(int));
// Add two rows
data.Rows.Add(1);
data.Rows.Add(2);

var q = conn.Query("myProc", new {data}, commandType: CommandType.StoredProcedure);

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