Check DB Connection from Installer

[aNoNameMoose]

Hello!

I have the current problem at hand.
I have a nicely working installer with several custom pages, mostly to configure some services we install.
I have a page that has fields that can be filled out that we will use to create a database connection. (The full connection string is assembled by a powershell script)
I would like to have a button on the page (this part is done) and have it's OnClick function check if the data that was filled in can make a successful connection to the database.

Function OnClick
MSSQL_OLEDB::SQL_Logon "servername\sqlexpress" "username" "password"
Pop $0
MessageBox MB_OK|MB_ICONSTOP "You clicked me and the result was $0" /SD IDOK
FunctionEnd

According to the plugins' very miniscule documentation I always get the error code, 1
I'm not sure what I'm doing wrong.
Is it not compatible? I have 2019 SQL Express server installed
It's configured for mixed authentication (windows/sql server), I tried both in the installer, always get the error code 1.
Any tips?

[Anders]

If your installer is Unicode you need to use UMSSQL_OLEDB?

Make sure the server name is correct.

[aNoNameMoose]

Thank you, that worked for both authentication types.
I feel silly for not trying it earlier.

If I may ask another question, how do I tell if something is Unicode or not? What does that mean?
I know it's to do with encoding characters but I guess I'm not grasping what it really means

[Anders]

DOS and Windows 95/98 uses "ANSI" codepages and so does NSIS v2 (and NSIS v3 with "Unicode False"). Typically 1 byte per "character".

NSIS v3 now defaults to Unicode. On Windows this uses the UTF-16LE encoding, typically 2 bytes per "character".

Unicode supports all languages and character scripts. Windows NT and later has two versions of all functions that take a string as input/output, one for ANSI codepages and one for Unicode. When using plug-ins, they must match the character encoding of the installer...