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Determine whether I have a valid connection to a SQL database

Posted on 2016-07-26
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Last Modified: 2016-07-31
I have the following code which attempts to create a query and recordset to determine whether the parameters in a form for ServerName and dbName are valid:

strDriver = "SQL Server Native Client 11.0"
cnn = "ODBC;DRIVER=" & strDriver & ";SERVER=" & ServerName _
    & ";Trusted_Connection=Yes;APP=Microsoft Office 2003;WSID=" & ServerName _
    & ";DATABASE=" & DBName & "; "
Set db = CurrentDb
Set qdf = db.CreateQueryDef("")
qdf.Connect = cnn
qdf.ReturnsRecords = True
qdf.SQL = "SELECT top 1 dbo.SomeTableName. * from dbo.SomeTableName"
Set rs = qdf.OpenRecordset()
rs.Close

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This code bombs out on the line that starts: SET rs =

With an error that reads:

 3151         ODBC--connection to 'SQL Server Native Client 11.0ServerName' failed.

But if I copy the connection string generated above:
ODBC;DRIVER=SQL Server Native Client 11.0;SERVER=ServerName;Trusted_Connection=Yes;APP=Microsoft Office 2003;WSID=ServerName;DATABASE=dbName;

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and create a new pass-through query with identical SQL string, it returns the 1 record I'm looking for, so the connection is valid, but I keep getting this error message.

Any ideas what I might be doing wrong?
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Question by:Dale Fye (Access MVP)
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13 Comments
 
LVL 84

Assisted Solution

by:Scott McDaniel (Microsoft Access MVP - EE MVE )
Scott McDaniel (Microsoft Access MVP - EE MVE ) earned 250 total points
ID: 41730250
What's the reasoning for creating a QueryDef and then opening the Recordset? In other words - why not just open the Recordset directly:

strDriver = "SQL Server Native Client 11.0"
cnn = "ODBC;DRIVER=" & strDriver & ";SERVER=" & ServerName _
    & ";Trusted_Connection=Yes;APP=Microsoft Office 2003;WSID=" & ServerName _
    & ";DATABASE=" & DBName & "; "
Dim rs As New ADODB.Recordset
rs.Open "Your SQL", cnn
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Author Comment

by:Dale Fye (Access MVP)
ID: 41730262
Scott,

Guess I'm just used to working with DAO, and rarely use ADO.  I'll give that a try.

Dale
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LVL 47

Author Comment

by:Dale Fye (Access MVP)
ID: 41730367
Scott,

I'm getting an error:

-2147467259   [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified

But with the exact same SQL string with is assigned to the linked tables
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LVL 84
ID: 41730372
Try a different connection string:

Provider=SQLNCLI11;Server=myServerAddress;Database=myDataBase;Uid=myUsername;
Pwd=myPassword;

REfer to here for more info on strings:

https://www.connectionstrings.com/sql-server/
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LVL 70

Expert Comment

by:Éric Moreau
ID: 41730391
what do you have in your ServerName  and DBName variable? what if you do Msgbox(cnn)? Do you see a valid connection string?
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Expert Comment

by:bfuchs
ID: 41730542
I tried your code with DSN like following and worked. (A2003)

ODBC;DSN=MyDbName;UID=MyUserName;PWD=MyPwd;DATABASE=MyDbName
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Expert Comment

by:Olaf Doschke
ID: 41730753
qdf is created in CurrentDb, and then you set a connstring? To the same database? Another? Forget this, if it is normal, I don't work much with Access, but it seems odd to root a querydefinition in some database and then impose a new connection on it.

Bye, Olaf.
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LVL 47

Author Comment

by:Dale Fye (Access MVP)
ID: 41732103
OK, so this is really strange.  Assume:

ServerName = "XXX"
DBName = "YYY"

I found that if I construct my connection string dynamically at runtime (lines 1&2) below, I get an error message on the rs.Open line below.  But if I define the connection string as depicted in lines 3&4, the recordset opens properly.  Anybody have any ideas?
'   strConn = "DRIVER={SQL Server Native Client 11.0};" _
            & "SERVER=" & ServerName & ";DATABASE=" & DBName & ";Trusted_Connection=Yes;"
    strConn = "DRIVER={SQL Server Native Client 11.0};" _
            & "SERVER=XXX;DATABASE=YYY;Trusted_Connection=Yes;"

    Dim rs As New ADODB.Recordset
    rs.Open "SELECT COUNT(*) as RecCount FROM SomeTable", strConn

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Prior to running this segment of code, I get the ServerName and dbName from the registry, use the NZ() function to give them a default value and then TRIM() the values to make certain that the strings don't contain any extraneous characters.  

When I print the connection strings, they are identical but the first returns the error:

-2147217843   [Microsoft][SQL Server Native Client 11.0][SQL Server]Cannot open database "YYY" requested by the login. The login failed.
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LVL 47

Author Comment

by:Dale Fye (Access MVP)
ID: 41732138
I'm an idiot, or I need better glasses.

The dbName variable contained an underscore instead of a hyphen in one character and I kept missing it when I looked at the error message and the connection strings when printed, one above the other.

Thanks all, for you help and recommendations.  I actually prefer the ADO method you show above Scott, over the querydef method I've used in the past.

Dale
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Accepted Solution

by:
Éric Moreau earned 250 total points
ID: 41732199
so my comments in ID 41730391 were on the spot!
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LVL 84
ID: 41732819
I'm an idiot, or I need better glasses.
I always blame it on the glasses!!

Glad you got it sorted. I much prefer to use the ADO method when working with SQL Server (or any other server database, for that matter).
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LVL 29

Expert Comment

by:Olaf Doschke
ID: 41732825
Indeed. But it shows you better compare good vs bad connection string programmatically...

https://youtu.be/Dkjkh3OrjeA?t=2m56s

Bye, Olaf.
0
 
LVL 47

Author Closing Comment

by:Dale Fye (Access MVP)
ID: 41736825
Thanks, guys
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