Migrate V3 to V4 string database

Hello, I used V3 3.034. I’ve installed V4 4.1.7 but connection string doesn’t work.
On V3 : Data source=localhost\SAMBAPOS3; User Id=sa; Password=sambapos
I use SQL SERVER 2012
Which connection string have I to enter on V4?
I followed the tutorial so I entered : data source=.\SQLEXPRESS;database=SAMBAPOS3; User Id=sa; Password=sambapos; but it doesn’t work

Your connection string does not seem right. V4 connection string should be exactly same with V3 connection string. The only addition to the V4 should be Database=SambaPOS3. In your example your v3 data source value is localhost\SAMBAPOS3 but you used .\SQLEXPRESS value for V4. It should be your SQL Server instance name.

Ok thanks,
when I followed the tutorial I didn’t understand it.
I used .\SQLEXPRESS because in the tutorial it’s written that.
sorry I’m not very gifted :-/

Actually, I just have to copy V3 connection string and add “database=SAMBAPOS3”
On V3 my connection string is : Data source=localhost\SAMBAPOS3; User Id=sa; Password=sambapos
So on V4 my connection string must be : Data source=localhost\SAMBAPOS3; database=SAMBAPOS3; User Id=sa; Password=sambapos

Now it works fine