Year and text string in conn string C#

Question

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I need to put year in database name connection string

Need to be

const string strCon2 = "Data Source=.\\SQLEXPRESS;Initial Catalog=BSS 2022;Integrated Security=True";

C#

I try to solve initial catalog

string year = DateTime.Parse(DateTime.Now.ToString()).Year.ToString();
const string naziv = "BSS ";
string konekcija = string.Concat(naziv, DateTime.Parse(DateTime.Now.ToString()).Year.ToString());

C#

And result

const string strCon2 = "Data Source=.\\SQLEXPRESS;Initial Catalog="+konekcija+";Integrated Security=True";

C#

or

const string strCon2 = "Data Source=.\\SQLEXPRESS;Initial Catalog=BSS "+year+";Integrated Security=True";

C#

But I have error

A field initializer cannot reference the non-static field

What I have tried:

C#

const string strCon2 = "Data Source=.\\SQLEXPRESS;Initial Catalog=BSS "+year+";Integrated Security=True";

Posted 15-Dec-22 1:16am

Stylus STYLUS

Updated 15-Dec-22 1:47am

PIEBALDconsult

v3

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OriginalGriff · Accepted Answer · 2022-12-15T01:47:00

Solution 1

You can't assign anything to a const field unless that initial value can be determined at compile time.

Use a readonly field instead, and set the value in the class constructor.

Posted 15-Dec-22 1:47am

OriginalGriff

Comments

Stylus STYLUS 15-Dec-22 7:51am

Example?

OriginalGriff 15-Dec-22 8:18am

Example of what? You know how to use readonly and what a constructor is don't you?

Richard Deeming 15-Dec-22 9:03am

Based on the DateTime.Parse(DateTime.Now.ToString()) in the question, I'm not so sure. :)

Stylus STYLUS 15-Dec-22 9:07am

This is my conecction string

const string strCon2 = "Data Source=.\\SQLEXPRESS;Initial Catalog=BSS "+year+";Integrated Security=True";

Defined year
private readonly string year = DateTime.Now.Year.ToString();

This part of con string "+year+"; is problem

Error CS0236 A field initializer cannot reference the non-static field, method, or property 'Program.year'

Richard Deeming 15-Dec-22 9:09am

Yes, as we keep telling you: a constant cannot refer to a non-constant value.

You need to make the field static and readonly. As I showed you below.

Richard Deeming 15-Dec-22 9:05am

private static readonly string year = DateTime.Today.Year.ToString();
private static readonly string strCon2 = "Data Source=.\\SQLEXPRESS;Initial Catalog=BSS " + year + ";Integrated Security=True";

Or:

private static readonly string strCon2 = $"Data Source=.\\SQLEXPRESS;Initial Catalog=BSS {DateTime.Today.Year};Integrated Security=True";

If you're doing this inside a method, remove the private static readonly prefix.

But using a different database for each year seems like an extremely poor design.

Stylus STYLUS 15-Dec-22 9:13am

That is solution. Thank you