Database Connection State

Recommended Posts


I am inserting data to my Database which is MS Access.

Using following code I open database connection,

dbase2_A1 = db.OpenEx("Driver={Microsoft Access Driver (*.mdb)};Dbq="+Registry.strPath_A1[0]+".mdb;Uid=Admin;Pwd=;")

Registry.strPath_A1[0] is string of my database path.

db.Execute(dbase2_A1,"INSERT INTO Final2(Test_ID) values ( '"+ C1_[0] +"')")

 it's working fine.

Now would like to check database connection ether it is open or close. 


Link to comment
Share on other sites

There is no way to tell if the connection is open or closed until you try a query or other command.  If that command fails, and you don't have malformed SQL, then the connection closed.  You could always do a simply query like "select now()", then catch any errors:

function checkDBConnection(dbHandle)
      db.execute(dbHandle, "select now();")

This will just return 1 if the connection is active, and 0 if it fails.  Now() is a MySQL function.  I am assuming it is also available in Access, but you get the idea.  Notice how I didn't bother with using Query() as that would require DAQFactory to actually process the result.  Since we just want to check the connection we can just use execute() with a super simply query that does not depend on database schema and ignore the result of the query.

Link to comment
Share on other sites

Thank You.

However we are new to the use of function. So, could you explain a bit elaborately. Also, after  taking use of  the mention code, couldn't figure out where would the 0 or 1 be obtained. Also, there is no mention of the use of function in the user guide pdf.

Link to comment
Share on other sites

This is a function I just wrote to solve your problem.  It won't be in the user's guide, but everything in it is in the user's guide.  Creating a function in DAQFactory from a sequence is section 5.17.   So is the return() statement. Try/catch is described in 5.19.  db.execute() you are already familiar with, but is in 9.5.  All I am doing is calling the simplest of SQL commands (the db.execute() line).  If it is successful, the next line will run which will return a 1 from the function.  If it fails, an error is thrown which causes the script to jump to the catch() line, which returns a 0 from the function.  So, anytime you call checkDBConnection() you will get a 1 if the connection is good, and 0 if it not.  What you then do with that is up to you.  I do not recommend displaying a message box if it fails if you are checking in a loop or the operator will never be able to dismiss it.  A better solution would be to close the existing connection handle and open a new connection.  


Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.