[Tutor] How to write database-agnostic python code? (Is this even possible?)

[boB Stepp]

On Tue, Sep 12, 2017 at 2:17 PM, Mats Wichmann <mats at wichmann.us> wrote:
> On 09/12/2017 01:05 PM, boB Stepp wrote:
>> As I continue to read about SQL, one thing jumps out:  There are many
>> differences between how SQL statements are implemented among the
>> different database products.  Even for relatively simple,
>> straightforward things like field concatenation.  One DB might use
>> "||" as the operator.  Another uses "+".  Yet another only uses a
>> "CONCAT" function.  This is crazy!

[...]

> But dealing with "local extension to SQL" is a different problem.  SQL
> is actually a standard and should work the same everywhere, but then
> people decide they need to improve it.  Being agnostic means avoiding
> mysql-specific syntax, postgres-specific syntax, etc.  Which means you
> need to know what is specific in the first place...

In the example I was alluding to, concatenating fields, surely this is
a "standard SQL" query?  So, for instance, if I had a Sales table with
FirstName and LastName fields and wanted to use SQL to get the full
name from these:

1) In Microsoft SQL Server:
SELECT
FirstName + ' ' + LastName
FROM Sales

2) MySQL:
SELECT
CONCAT(FirstName, ' ', LastName)
FROM Sales;

3)SQLite:
SELECT
FirstName || ' ' || LastName
FROM Sales;

And these would be the SQL commands/statements I would have
cursor.execute use from the sqlite3 module.  They would be different
depending on which database product I was using.  Am I horribly
misunderstanding something???  And if not, I have several other
apparently fundamental SQL examples where similar situations exist
based on the book on SQL I am only 43 pages into!

-- 
boB