Unsure which join to use with with the following sql code - sql-server

Question

i have 2 tables. I am wanting to insert some values into 1 table. The fields i am updating is ingredient_Name, Ingredient_Amount and Recipe_ID.
Ingredient (Table 1)
Ingredient_Name|Ingredient_Amount|Recipe_ID
---------------|-----------------|--------- <---- Insert into here
Recipe (Table 2)
Recipe_Name|Recipe_ID
yummyRecipe|----1---- <-----Recipe_ID stored here
The form i am using has a comboBox which lists all Recipe_Names. So when i go to insert a row into ingredients i need to fetch the Recipe_ID from the Recipe table where i have selected the Recipe_Name in the comboBox. Then use this Recipe_ID for the ID in the Ingredients table.
I am not very familiar with JOINs and unsure how to work out what one to use and if i need to use one. Any help or ideas?
Sorry if this is too long winded.
Recipe ComboBox Code
SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\v11.0; AttachDbFilename=C:\Users\Donald\Documents\Visual Studio 2013\Projects\DesktopApplication\DesktopApplication\Student_CB.mdf ;Integrated Security=True");
con.Open();
try
{
SqlDataAdapter da = new SqlDataAdapter("Select * FROM Recipe", con);
DataTable dt = new DataTable();
da.Fill(dt);
for (int i = 0; i < dt.Rows.Count; i++)
{
recipeCombo.Items.Add(dt.Rows[i]["Recipe_Name"]);
}
dt.Clear();
}
catch (Exception e)
{
MessageBox.Show(e.Message);
}
con.Close();

Answer 1

You can set the ComboBox items using directly the DataSource and control which field you want to display using the DisplayMember property. Together with the ValueMember property you could write
using(SqlConnection con = new SqlConnection(....))
{
con.Open();
try
{
SqlDataAdapter da = new SqlDataAdapter("Select * FROM Recipe", con);
DataTable dt = new DataTable();
da.Fill(dt);
recipeCombo.DataSource = dt;
recipeCombo.DisplayMember = "Recipe_Name";
recipeCombo.ValueMember = "Recipe_ID";
}
catch (Exception e)
{
MessageBox.Show(e.Message);
}
}
Now in the ComboBox_SelectedIndexChanged event (or everywhere you need to know the RecipeID you just have to write
if(recipeCombo.SelectedItem != null)
{
int recipeID = Convert.ToInt32(recipeCombo.SelectedValue);
... and use your value for insert without any JOIN
}
In whichever point you need, (for example in a SAVE button click event) add the following INSERT
if(recipeCombo.SelectedItem == null)
.... error message and return....
else
string sql = #"INSERT INTO Ingredient
(Ingredient_Name, Ingredient_Amount, Recipe_ID)
VALUES (#IngredientName, #IngredientFirstname, #RecipeID)";
using (var cmd = new SqlCommand(sql, con))
{
cmd.Parameters.Add("#IngredientName", SqlDbType.NVarChar).Value = ingredientTxt.Text);
cmd.Parameters.Add("#IngredientAmount", SqlDbType.Integer).Value = Convert.ToInt32(ingredientAmount.Text);
cmd.Parameters.Add("#RecipeID", SqlDbType.Integer).Value = Convert.ToInt32(recipeCombo.SelectedValue);
cmd.ExecuteNonQuery();
}
PS. Do not use AddWithValue - it is a shortcut with a lot of problems -

Answer 2

You do not need a JOIN in your case because you have only one table "Recipe" that contains the data you need to find "Recipe_ID". JOINs are used to "join" two tables.
If "Recipe_Name" is identical you can select the "Recipe_ID" where the "Recipe_Name" is equal to the selected value from the combobox then insert the new row to the "Ingredient" table.
INSERT INTO Ingredient SELECT #Ingredient_Name, #Ingredient_Amount, Recipe_ID FROM Recipe WHERE Recipe_ID = #myComboboxSelectedValue
Note: In this case Recipe_ID is redundant because you can remove it from your database and use Recipe_Name instead.
If "Recipe_Name" is not identical so you will need to fetch "Recipe_ID" with it and store it in the code-behind (if you do not want to show it to the user) and use it in your insert query.
By the way:
4. Whether using MYSQL or SQLSERVER the solution is the same, so "using .mdf" in the title of the question is irrelevant.
5. ".mdf" files are the extensions for SQLSERVER databases.