نکته

On 14th December 1900, German theoretical physicist Max Plank published his seminal paper on the Quantum Theory of Radiation, and quantum physics was born! In the early years of the 20th century, quantum physics was further developed and applied to explain several other experiments by Albert Einstein, Paul Dirac, Neils Bohr and many others.

Quantum theory is extremely non-intuitive, and came as a shock to the physics community, shaking the foundations of scientific knowledge. American physicist Richard Feynman once said, “I think I can safely say that nobody understands quantum mechanics.”

Though a century old now, its interpretations still puzzle scientists and students alike, making it a hot topic for research, with new ‘theories’ coming up all the time!

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SET versus SELECT when assigning variables?

SET is the ANSI standard for variable assignment, SELECT is not.

SET can only assign one variable at a time, SELECT can make multiple assignments at once.

If assigning from a query, SET can only assign a scalar value. If the query returns multiple values/rows then SET will raise an error. SELECT will assign one of the values to the variable and hide the fact that multiple values were returned (so you'd likely never know why something was going wrong elsewhere - have fun troubleshooting that one)

When assigning from a query if there is no value returned then SET will assign NULL, where SELECT will not make the assignment at all (so the variable will not be changed from its previous value)

As far as speed differences - there are no direct differences between SET and SELECT. However SELECT's ability to make multiple assignments in one shot does give it a slight speed advantage over SET.