Intro to SQL. Live learners, anonymised answers from everyone who took this before, and partners Mira plays from those same patterns. You can see which is which.
47 answers · stacked live, archive, and Mira
You ask for orders where the channel is not email. Thousands of rows vanish. Where did they go?
“If they vanished they must have been email all along. The filter caught them.”
a data apprentice · 7 found this useful
“If the cell is empty it didn't happen, so it's a zero, right? That's how every spreadsheet I've used works.”
someone in their first SQL week · 19 found this useful
“Unknown isn't false. The filter only keeps a row when the test is definitely true. A blank channel isn't 'not email' — it isn't anything. That's why 4,000 people dropped out of our campaign report.”
an analyst at a retailer · 48 found this useful
“Zero spend is a fact: they bought nothing. Missing spend is we never wrote it down. Only one of those can go in a total. I lost a board slide to that.”
a founder doing their own reporting · 31 found this useful
“There's a bug in the filter. Missing isn't email, so those rows should stay. I'd file a ticket.”
a product manager · 8 found this useful
Vote to add yourself to the live tally.
Mira seats you with someone holding a named wrong idea — a live peer, an echo replayed from the archive, or a partner she plays herself.
Talk Jonas out of empty meaning zero
Jonas thinks “empty means zero, or means an empty bit of text”
Replay: a filter that keeps the benefit of the doubt
a product manager thinks “a filter keeps a row unless it clearly fails the test”
Priya still wants every column after grouping
Priya thinks “I can still ask for any column I like once I have grouped”
Talk Jonas out of LIMIT making it faster
Jonas thinks “keeping only five makes the query faster because it stops early”
Comments, votes, and the wording that actually landed — anonymised, and still in the room.
“Vanishing rows first. That's the one that bit our campaign report — nothing errored, the number was just too small.”
“Is grouping just a pivot table? I already do that in a spreadsheet.”
“If they vanished they must have been email all along. The filter caught them.”
“There's a bug in the filter. Missing isn't email, so those rows should stay. I'd file a ticket.”
“I'm in the lesson now — so the blanks failed the 'not email' test?”
“I asked for orders that are not email. The blanks aren't email. Why do they vanish too?”
“Unknown isn't false. The filter only keeps a row when the test is definitely true. A blank channel isn't 'not email' — it isn't anything. That's why 4,000 people dropped out of our campaign report.”
“That's the one that landed for me. I had been treating blanks like they failed the test. They didn't fail. They never got a chance.”
“If the cell is empty it didn't happen, so it's a zero, right? That's how every spreadsheet I've used works.”
“Zero spend is a fact: they bought nothing. Missing spend is we never wrote it down. Only one of those can go in a total. I lost a board slide to that.”
“Once I've stacked the rows by channel, can I still ask for the customer name? It's right there in the table.”
“Forty names in that stack. Which one should it show you? Once they're stacked, the only things with one clear value are what you grouped by and the number you worked out.”
“LIMIT 5 makes it faster because it stops after five, right? Less comes back so less work happened.”
“To know which five are biggest it has to work out all of them and put them in order first. Then it throws the rest away. Same two moves as keeping the closest few pages.”
“I keep wanting SELECT * after the group. The editor is yelling and I don't know which line is the actual idea.”
“Does ORDER BY happen before or after the group? I keep reading it top to bottom.”
“WHERE channel != 'email' — that's the same trap as the 4,000. I'd reject this. The total will go quietly small and nothing will error.”
“I'd have approved this. It looks right. Email is gone, the totals still add up on screen.”
“The wording that landed for me: unknown isn't false. Say that at work and people stop treating blanks like zeroes.”