问题
I have been connecting to my local database (SQL Express) fine all day from my C# console application.
I have made an update, where I create a database and table from within the C# code using ADO.NET
When I do this, my normal connection string fails, which is
Data Source=.\\sqlexpress; Trusted_Connection=True; Initial Catalog=ThisIsMyDataBase;
The error message is
Cannot open database "ThisIsMyDataBase" requested by the login. The login failed.\r\nLogin failed for user 'My-PC\\MrD'.
If I open the tables in SSMS, then I can access everything, using Windows Authentication.
I was under the impression that the Trusted_Connection=True would mean I have permission, and that I'm accessing it with my Windows account (not an SQL account) would mean I don't see this issue, but I'm clearly wrong. I'm not sure how to solve this.
回答1:
The error itself is saying the user dont have access failed for user 'My-PC\\MrD'. do a login for the user from sql server itself
回答2:
You propably do not have the sql server login, which is associated with your WIN user, mapped to a database user.
Check that your model database (under System databases in management studio) has your WIN user listed under Security/Users. If not, add it. Then delete the MyDb database and create it again using you code. The CREATE DATABASE statement uses a copy of the model database to create the new database and its metadata.
回答3:
I have the solution but I don't understand it at all
The answer is to rename the database with less characters. My actual database was 27 characters long, I've just given it a 4 character long name (simply called My01) and it works fine.
来源：https://stackoverflow.com/questions/30212318/cannot-open-database-mydb-requested-by-the-login-the-login-failed-login-fail