In the SQL Server error log file I found the following lines:
2018-02-22 14:10:58.95 spid17s Starting up database 'msdb'. 2018-02-22 14:10:58.95 spid16s Starting up database 'ReportServer'. 2018-02-22 14:10:58.95 spid18s Starting up database 'ReportServerTempDB'. 2018-02-22 14:10:58.95 spid19s Starting up database 'XYZ'.
If I check for the status of the database XYZ before this time, it is
ONLINE using the following statement:
SELECT state_desc FROM sys.databases WHERE name='XYZ'
...but when I try to connect to this database using a C# application, it can't connect to the database.
The error is:
Login failed for user 'asd'.
Reason: Failed to open the explicitly specified database.
I tried three different users (Windows user, sa, SQL Server user defined for the application). The problem happens when I run the application in the start up of the OS, but if I start it manually after the start up, no errors happen, so I think all SQL Server settings and firewall settings are correct.
I also checked before this that the service status is running.
What else should I check to make sure the database is actually online and ready for queries?
I'm looking for a key that tells me it's ok to query the database, instead of delaying for a time (even not based on a clear reason).
I thought of scanning the error log for the text "Starting up database 'XYZ'", but this means I have to add a setting for the application for the path of the SQL Server error log. It also means reading the file many times until I find this phrase.