SQL Wrappers
- From: "David Cressey" <david.cressey@xxxxxxxxxxxxx>
- Date: Fri, 09 Dec 2005 13:42:52 GMT
The recent discussion about SQL-wrappers reminded me of something.
I once worked with a dialect of SQL that provided access to data stored in
files as well as data stored in a database.
The format of the files was comma separated values (CSV), the access was
read only, and a secondary file was needed to declare the column names,
among other things.
In that context, it was straightforward to code something into the CSV file
that would result in a NULL being passed to the SQL user. All you had to do
was code two commas in a row. Since there was nothing between the commas,
the wrapper generated a NULL.
That raises the question, how do you pass an empty string? The answer was
that you had to put a pair of quote marks between the two commas in the CSV
file. The two quotes explicitly marked a string, and the fact that there
was nothing between them marked an empty string. This was a nuisance, to be
sure, but it was a minor nuisance.
All of this raises another question for me. When is SQL NOT a wrapper?
.
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