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Why can joining two tables create more rows than you started with?

If a value matches several records, a database join can produce several rows for that one value. A repeated name may therefore behave very differently from a unique customer identifier. Understanding what each joined row represents is essential before adding amounts or counting customers.

8–10 min

Questions you could explore

  • What is the difference between no matching order and an order with a value of zero?

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Computers and AI

Why can a damaged QR code still work?

A scratch or stain does not always stop a QR code from being read. Its stored information includes redundancy, but that does not mean any part of the image can be covered without consequence.

3–5 min

Why can a damaged QR code still work?

Computers and AI3–5 minA scratch or stain does not always stop a QR code from being read. Its stored information includes redundancy, but that does not mean any part of the image can be covered without consequence.

Computers and AI

How does a website name become an internet address?

You remember a website by its name, while the network needs an address for the connection. DNS supplies that translation, sometimes from a saved answer and sometimes by asking other servers.

4–5 min

How does a website name become an internet address?

Computers and AI4–5 minYou remember a website by its name, while the network needs an address for the connection. DNS supplies that translation, sometimes from a saved answer and sometimes by asking other servers.

Computers and AI

Same emoji, different picture

The same emoji can arrive with a different expression or style from the one you saw when sending it. Unicode identifies characters and sequences, while software platforms choose artwork and decide what their versions support.

2–3 min

Same emoji, different picture

Computers and AI2–3 minThe same emoji can arrive with a different expression or style from the one you saw when sending it. Unicode identifies characters and sequences, while software platforms choose artwork and decide what their versions support.

Why can joining two tables create more rows than you started with? | Speech Topic | speaking.app