Verifying Database Writes Good Practice?

[Avochelm]

I know for certain that in lower level applications, verfying a data write is very good practice. When inserting data into MySQL would it be nessecary to do a second query to look up the row to see if it exists with all of the correct data or should I use a built in function of PHP?

Eg: Would this be sufficient:

$result = mysql_query($sql);

if ($result==false) {
  print "Possible Error";
}
else {
  print "Query Completed (& Verified?) Successfully";
}

[laserlight]

Well, the problem with such verification would be server load, so one would probably assume that if the query was executed ok, the data should be written ok.

[Avochelm]

Makes sense. Cheers.

[planetsim]

You can use

mysql_affected_rows();

That will verify the affected rows from a query

[drawmack]

Step 1) Verify data integrity
Step 2) Construct query
Step 3) Execute query
Step 4) use the return from the execution function to verify that the query was executed.

That way you only have the server load of one query. The assumption is that your data integrity rules are tight enough that if it passes them it will insert properly.