How to retrieve values from a Database for computation?

Question

How to retrieve values from a Database for computation?

VKSB 236

Hi all,

I am writing an Astrology program, where I need to use Latitude & Longitude of places for the calculation to create a Horoscope. I have made a Database of Latitude & Longitude of places.

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I couldn't find out how to get the values of Latitude & Longitude of a particular place (city) from the Database to compute the planetary positions.

For an example, I want to get the Latitude & Longitude of "Liverpool" for the calculation. I know how to search for "Liverpool" but couldn't figure out how to get the "Values" of Latitude & Longitude.

Could you please let me know how to do this?

Thanks,

VKSB

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Answer 1

Michael Taylor 61,096

Are you already hooked up to your Access database in your application? If so then what data access library are you using? Posting any relevant code would be useful.

As for how to get the data from Access (or any database) then something like this works.

SELECT Latitude, Longitude FROM <tablename> WHERE City = 'Liverpool'

VKSB 236 Reputation points

2024-03-05T17:33:22.6133333+00:00
Hi Michael Taylor,

I've connected the Access Database, have made the "DataGridView" & "Details" & can use the "BindingNavigator".

***"*If so then what data access library are you using?"

I don't know what is "Data access Library" ? Could you please explain it to me.

SELECT Latitude, Longitude FROM <tablename> WHERE City = 'Liverpool'

In the above given code, I hope that I can use a "Variable" for the Name of "City" selected for the calculation instead of 'Liverpool'; am I correct?

Please let me know.

Thanks

VKSB
VKSB 236 Reputation points

2024-03-05T17:42:51.03+00:00
Hi Michael Taylor,

I've connected the Access Database, have made the "DataGridView" & "Details" & can use the "BindingNavigator".

"If so then what data access library are you using?"

I don't know what is "Data access Library" ? Could you please explain it to me.

SQLCopy

SELECT

In the above given code, I hope that I can use a "Variable" for the Name of "City" selected for the calculation instead of 'Liverpool'; am I correct?

Please let me know.

Thanks

VKSB
Michael Taylor 61,096 Reputation points

2024-03-05T18:36:12.1666667+00:00
Please use the Add comment feature to respond to answers so comments are associated with the answer you're responding to.

Data access library - ADO.NET? (e.g. OleDbConnection, OleDbCommand, etc). Please post some sample code of how you're populating your datagrid's data source.

Assuming you're using OleDbCommand or similar then parameterizing a query is straightforward.

var cmd = new OleDbCommand("SELECT Id, Latitude, Longitude FROM <table> WHERE City = ?", conn); //OLEDB is positional based so ensure parameters are added in order they //are used in query cmd.Parameters.AddWithValue("?", "Liverpool");
VKSB 236 Reputation points

2024-03-06T10:37:58.3566667+00:00

Hi Michael Taylor,

I am following the book "Microsoft Visual Basic 2005 Step by Step"; it uses ADO.NET.

Using the methods given in that book, I drag the "Objects" from the "Data Source Window" to the "Form Designer"; this places the "DataGridView" and / or "Details" and also the "BindingNavigator" tool bar.

This populates DataGridView on clicking the "Debug" button.

Hope this answers your questions.

Thanks

VKSB
Michael Taylor 61,096 Reputation points

2024-03-06T15:04:53.87+00:00

That helps a little but I don't have that book so I'm only guessing what you're doing.

The Objects data source is used to bind to data that is already in your application via other means. In order to use it you would have had to create business objects that call Access and then you can bind to your business objects. What we would need to see is that set of objects that you're using to get data from Access using your custom types.

Do you have any code that gets OleDbConnection or similar?

I would sort of expected you to be using a typed dataset which was generated by selecting Database in the data source wizard. It would have then auto-generated a lot of code to get the data from the database for you.

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How to retrieve values from a Database for computation?

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