Insert data in MySQL db in all tables

here I'm again for some help. :) I'm trying to insert data into my MySQL database using F#. My schema includes 3 tables (Experiments, Gene and Results):

Experiments         |       Results           |        Gene 
Experiment id       |       Experiment id     |        Gene id 
Experiment name     |       Gene id           |        Gene Name                         
                    |       Value             |

Now, I'm trying to add data into the db using SQLProvider.

let db = sql.GetDataContext()

let gene_tb = db.Vp32.Genes
let exp_tb = db.Vp32.Experiments
let results_tb = db.Vp32.Results

let createNewInput (genename: string) (expname: string) res =
    let newRes = results_tb.Create()
    let newGene = gene_tb.Create()
    let newExp = exp_tb.Create()

    newGene.GeneName <- genename
    newExp.ExpName <- expname
    newRes.ResultVal <- Some res

createNewInput "test1"  "experiment_test1" (float32 999.5)

db.SubmitUpdates()

I'm having problems to make it understand that the result value is linked to the experiment and gene ids. It gives an error when I try to submit it: "Field 'Exp_id' doesn't have a default value". Well, there isn't a default value because it should be the ids of the other tables. Oh, and.. these IDs are set to auto increase. Moreover, everytime I add new data, if the experiment name exists already in the table, the id shouldn't increase. Do I have to do something like a 'trigger' for this or some specification code using 'if...then'?

Thank you very much in advance! :D Thanks to you I've already learned sooo much alredy, I can't believe! ^-^

SOLUTION: So, I found out that the problem was that I had to query the IDs of Experiments and Genes.. So I changed stuff a bit. For now I have 3 functions (one for each table) and the one for results do a small query before adding the result value:

let addNewExp (expname: string)=
    let newExp = exp_tb.Create()
    newExp.ExpName <- expname
    db.SubmitUpdates()

let addNewGene (genename: string)=
    let newGene = gene_tb.Create()
    newGene.GeneName <- genename
    db.SubmitUpdates()

let addNewRes (expName: string) (geneName: string) res =
    let tempExpId = 
        query {
            for experiment in exp_tb do
                where (experiment.ExpName = expName)
                select experiment.ExpId
            }
        |> Seq.head

    let tempGeneId = 
        query {
            for gene in gene_tb do
                where (gene.GeneName = geneName)
                select gene.GeneName
            }
        |> Seq.toArray |> String.concat ""

    let newRes = results_tb.Create()
    newRes.ExpId <- tempExpId
    newRes.GeneId <- tempGeneId
    newRes.ResultVal <- Some res
    db.SubmitUpdates()

Indeed, it's necessary to do the query to get the id values before adding something in the associative table (results). Afterwards I just converted to the correct types (that are described in the database) since the query returns as sequence (Seq). I hope this can also help someone in the future.