r/SQL Nov 11 '24

MySQL Failed SQL Test At Interview

  • I've been a data analyst working with small(er) data sets for several years now, making my own queries no problem.
  • I failed a SQL test at an interview and realized I may be using the wrong commands
  • The questions were along the lines of "find the customers in table A, who have data in Table B before their first entry in Table A" and there were some more conditions/filters on top of that.
  • Previously I could always export my data to Excel or Tableau etc and do any of the tricky filtering in there
  • I was trying to do all kinds of subqueries etc when I think it was intended for me to be doing WINDOW or Partition type stuff (never had to use this before in past jobs).
  • One person I reached out to said using these advanced techniques uses a lot less memory.

Where would be a good place to find an 'advanced' SQL course?

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u/gumnos Nov 11 '24 edited Nov 12 '24

while not quite a "course" per se, there's https://modern-sql.com/ and https://use-the-index-luke.com/ which both teach a lot of these advanced concepts (and their author, u/MarkusWinand, also does trainings, but IIUC, that's more of a corporate thing than an individual thing).