Common syntax in MySQL and MSSQL for IF INSERT ELSE UPDATE - php

Question

I have a PHP 7.3 project which connects via PDO to a MySQL database or a MSSQL database, depending on being run on Linux or Windows.
I want to insert a new values into a table, if the unique value is not yet in that table. If it is already in the table, I want to update the non-unique values.
I searched a lot of docs and SO posts, also, but I couldn't find a syntax, which does that in one query for both database types.
SQL Server query:
IF (EXISTS (SELECT * FROM failed_logins_ip_address WHERE ip_address = 'xxx'))
BEGIN
UPDATE failed_logins_ip_address
SET attempts_count = attempts_count + 1, attempt_datetime = CURRENT_TIMESTAMP
WHERE ip_address = 'xxx'
END
ELSE
BEGIN
INSERT INTO failed_logins_ip_address (ip_address, attempts_count, attempt_datetime)
VALUES ('xxx', 1, CURRENT_TIMESTAMP)
END
MySQL query:
INSERT INTO failed_logins_ip_address (ip_address, attempts_count, attempt_datetime)
VALUES ('xxx', 1, CURRENT_TIMESTAMP)
ON DUPLICATE KEY
UPDATE attempts_count = attempts_count + 1, attempt_datetime = CURRENT_TIMESTAMP
'ip_addess' column is unique, and the table structure is identical for both MSSQL and MySQL.
Is there a syntax, which can do an IF INSERT ELSE UPDATE in both database types?
Yes, I do (PDO) parameter binding, xxx is just to shorten the code snippet.
Yes, I could use identical syntax if I did it in two queries (first select, then insert or update) but I want to avoid (hopefully) unnecessary queries.
No, I do not want to insert every login attempt so I do not need the update anymore because I do not need this data.
If the REPLACE approach would work: this does not update, it deletes and inserts, which I also do not want.
My current solution: I check in PHP for the current database type and switch/case the query strings. It is clean but one string is even less smelly ;-)
UPDATE:
I changed the MSSQL query around: from of IF NOT EXISTS TO IF EXISTS to improve the efficiency. UPDATE will occur a lot more often than INSERT, so in most of the cases, only the first (sub)query will be executed.

Answer 1

After digging deeper, I found this post by a Derek Dieter, which describes how to replace SQL Server's IF EXISTS ELSE by WHERE EXISTS:
https://sqlserverplanet.com/optimization/avoiding-if-else-by-using-where-exists
The WHERE EXISTS syntax seems to be the same in MySQL and MSSQL.
Derek Dieter's example, with IF EXSISTS:
IF NOT EXISTS (SELECT 1 FROM customer_totals WHERE cust_id = #cust_id)
BEGIN
INSERT INTO customer_totals
(
cust_id,
order_amt
)
SELECT
cust_id = #cust_id
,order_amt = #order_amt
END
ELSE
UPDATE customer
SET order_amt = order_amt + #order_amt
WHERE cust_id = #cust_id
END
Derek Dieter's example, with WHERE EXISTS:
INSERT INTO customer_totals
(
cust_id,
order_amt
)
SELECT TOP 1 — important since we’re not constraining any records
cust_id = #cust_id
,order_amt = #order_amt
FROM customer_totals ct
WHERE NOT EXISTS — this replaces the if statement
(
SELECT 1
FROM customer_totals
WHERE cust_id = #cust_id
)
SET #rowcount = ##ROWCOUNT — return back the rows that got inserted
UPDATE customer
SET order_amt = order_amt + #order_amt
WHERE #rowcount = 0
AND cust_id = #cust_id — if no rows were inserted, the cust_id must exist, so update
I still have to test it, though, in MySQL. I'll update this post and add the code, if it works.

Answer 2

If you are using PHP, then you are calling the code through an interface. You can do the following:
Create a unique index on ip_address.
Attempt to insert a new row. This will fail if the row already exists.
If the insert fails (particularly with a duplicate key error), then update the existing row.
However, your goal of trying to have the same code in both databases is . . . just not going to work very well. The two databases are rather different. Perhaps you should consider constructing stored procedures in each database to do what you want and then calling those stored procedures.