SQLDataSource | SQL DataSource for Apollo GraphQL projects | GraphQL library

I'm running into a problem. I have .net core 3.1 web api that can successfully use GET method to fetch participant table data from a postgres localhost, but I cannot use POST method. Postman throws error ""Parameter '@FirstName' must have its value set"", despite giving it non null input. I'm not sure if the problem is I don't use postman properly or the C# code is wrong. I'm a newbie in .NET core 3.1 so any help is more than welcome.

Participant table:

First of all, sorry if I make mistakes in english...

I'm making a web with c#, and I have some problems for refresh the data displayed in the GridView

I'm getting the data throw the SqlDataSource defined at the aspx view:

For now I have a procedure I wish to call:

I am currently trying to have a select contain a default value in the options section, while also databinding it using a sqldatasource. I know that asp:Dropdowns have the appenddatabounditems attribute, but was curious if select controls also have something similar. Or if there is any way to do this at all.

I need to create a json from a regular column to a json with a key. Only I don't understand how to do it in c#. I am using Postgresql database and I need to keep separate data there, and I need to pass to the server via api as I indicated below

What I got is.

I have an ASP.NET HTML website in which I want to update my SQLDataSource SELECT command using a drop-down menu. The user can select to sort by Date, Duration or Player, and the GridView will update showing the new, sorted results from my mdf database. I'm really not sure at all how to approach this as I am fairly new to ASP.NET. I could just do with some pointers on how to go about it, and what method to use. I can google tutorials, the problem is knowing what to google. Any advice greatly appreciated :) My code:

I have a simple gridview with CSSClass for styling and its working fine, but the problem is when I click a button on gridview it disable the function of the CSSClass for example after I click the button the background color is removed I don't know why, here is my code:

I have a simple gridview that contains userID and user_name and a select button in each row,

I created a javascript function to display user ID and User Name from gridview to asp.net Texboxe user ID and Texboxe user Name by clicking on the select button, and its working fine,

but instead of using multiple buttons on each row I want to use a single button that can do the same thing based on the value on Texboxe user ID value,

for example if I typed user ID (1) on Texboxe user ID and then clicked the single button it show display the user name on Texboxe user Name

Is it possible to append to an SQL query based on number of clicks on a button?

Eg. For each time I click on the button (+) I want to add OR [PIN]=@LogID# Where # is a number increasing for everytime I press the plus (+) button.

I also would like do be able to decrease the same way by using the minus (-) button.

A new textfield should appear for every (+) click with the same number # as the appending line in the query OR [PIN]=@LogID# to my SQL query SelectCommand="SELECT * FROM [PINCode] WHERE ([PIN]=@LogID)". And decrease if I click on (-) button.

Any idea on how to do this? I would appreciate any links or suggestions pointing me in the right direction.

I´m not looking for a finished solution here just help on were to start. What to search for, where to read.

Implemented the example script recieved

Default.aspx.vb