Question

In the following code, I would like to insert or update rows in an SQL table through F#.
It takes a matrix of tuple representing users and an associated scores (usrID,score) which are the results of some F# calculations.
Now I want to update a SQL table called UserScoresTable.
The code I wrote is working but is very slow.

let cnn = new System.Data.SqlClient.SqlConnection(ConfigurationManager.ConnectionStrings.Item("Database").ConnectionString)
cnn.Open()

// Definition d'une fonction qui execute une demande sous MySQL
let execNonQuery s =
    let comm = new System.Data.SqlClient.SqlCommand(s, cnn, CommandTimeout = 10)
    comm.ExecuteNonQuery() |> ignore

// Definition d'une fonction qui utilise les éléments d'une matrice pour updater une table dans MySQL
let updateMySQLTable (m : Matrix<float * float>) =
    for j in 0 .. (snd m.Dimensions) - 1 do
        for i in 1 .. (fst m.Dimensions) - 1 do
        // first check if the user and score and date do not exist
            sprintf "IF NOT EXISTS (SELECT * FROM ProductScores WHERE UserID = %f AND ProductID = %f) INSERT INTO ProductScores (UserID, Score, Date) VALUES (%f, %f,CURRENT_TIMESTAMP)"  (fst m.[i, j]) (snd m.[i, j])
            |>  execNonQuery
       // otherwise update the row
            sprintf "UPDATE ProductScores SET Score = %f, Date = CURRENT_TIMESTAMP WHERE UserID = %f " (snd m.[i, j]) (fst m.[i, j])
            |>  execNonQuery

I would like to avoid the two execNonQuery requests in the code by using a stored procedure such as

CREATE PROCEDURE updateScoreByUsers 
    -- Add the parameters for the stored procedure here
    @UserID int, 
    @Score  float

AS
BEGIN

    IF NOT EXISTS 
    (SELECT * FROM ProductScores WHERE UserID = @UserID ) 
        INSERT INTO 
        ProductScores (UserID, Score, Date) VALUES (@UserID,@Score,CURRENT_TIMESTAMP)
    ELSE

    UPDATE ProductScores 
        SET Score = @Score, Date = CURRENT_TIMESTAMP 
        WHERE UserID = @UserID 
END
GO

But I don’t know how to call a SQL stored procedure in F#.
How can I call it with F#?
DO you see any other way of improvements?

Answer 1

Set SqlCommand.CommandText to the name of the stored procedure and set CommandType to StoredProcedure. For example

use cmd = new SqlCommand("MyStoredProcedure", con)
cmd.CommandType <- CommandType.StoredProcedure
cmd.ExecuteNonQuery()

If you’re on 2008 you may want to look into the MERGE statement.

To significantly improve performance you need to avoid making a database call for each item. Perhaps use SqlBulkCopy to load all the data to the server at once (use a temp table or designated staging table), then use set-based operations (UPDATE/INSERT/MERGE) to merge with your target table.