Question

I’m curios if this can be achieved as I’m currently facing a bug and would like to see if putting a SELECT and an UPDATE in a transaction would fix it (if you’re wondering why I’m not posting the code that causes the bug it’s because it’s a complex environment and I can’t post all the influencing factors).

Something that I’m also interested in, related to this, is if you have ever experienced code that had and UPDATE query written after a SELECT query, yet the UPDATE gets executed before the SELECT (with the possibility that the script might run twice ruled out).

Answer 1

It depends on what do you mean by a transaction.
There are two types of transactions:

• Implicit transactons: as in INSERT, UPDATE, SELECT, DELETE statements, and in such statements there is no explicit transaction commands, and the database engine will rollback the whole statement if an error happens.
• Explicit Transactions: in such the enclosed statements inside the transaction are executed as a unit and either COMMIT the whole transaction or ROLLBACK .

So you can’t have both SELECT and UPDATE inside one query, but you can but them inside a transaction like:

START TRANSACTION;
   SELECT * FROM tableName;
   UPDATE table SET something = 'other something' WHERE thirdsomething = @s;
COMMIT;

Then Put them in a stored procedure or a UDF.

Note that: SELECT statements do not modify data, so you might not need to enclose it in a transaction, so in your case you will have only UPDATE statement you can just use a stored procedure without a transaction.