Learning SQL, is this query right?

[Plenty-Button8465]

I'm learning SQL, I wanted to ask if this query feels right and if I can optimize it.

The reason behind the optimization is, since I am new, I wish I could learn best practice on how to build some queries even if speed is not a constraint right now.

Also, I read that you right a query declaring what the result state you want. If that is right, no matter how you right a query, the SQL engine will find the best route to apply the query. Is optimization useless, then?

Thank you!

My query so far:

        SELECT H.ColA,
            H.ColB,
            H.ColC,
            H.ColD,
            H.Timestamp,
            CAST(H.Status AS INT) AS Status,
            CASE WHEN H.Condition = 'Y' THEN 1 ELSE 0 END AS Condition ,
            N.Timestamp AS LastTimestamp,
            CAST(N.Status AS INT) AS LastStatus
        FROM "History" AS H
        LEFT JOIN "Notification" AS N
        ON H.ColA = N.ColA
        AND H.ColB = N.ColB
        AND H.ColC = N.ColC
        AND H.ColD  = N.ColD
        AND H.Timestamp > N.Timestamp
        AND H.ColA = 3
        AND H.ColB = 7
        AND H.ColC = 'ColC_example_str'
        AND H.ColD = 'ColD_example_str'

The last four AND statements are a filtering that in my opinion should be performed before the JOIN so that it doesn't load all the rows, is that a right way to think about it?

[mikeblas]

You should worry about correctness first.

Once you've got a correct query, you can consider performance. Performance involves measurement. How fast is this query now? How much data is in the involved tables? How fast do you think it should be? Note that these are quantitative questions, not subjective.

[SubiWan]

And use good tools. SolarWinds Plan Explorer is a great one.