All Questions
4 questions
0
votes
1
answer
103
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The most recent rows in for each type/agent
I have a table (still on MySQL 5.7) with lots of data. This table is written by some scripts. It works like a "checkin", where each agent is checking in in some period of time. It looks like ...
- 13
-2
votes
1
answer
24
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Extracting data from two tables
I have( for example) a table called A and a table called B.
Table A contains tons of user data( age, country bla bla) and is connected to B by forein_key=id( B only has ID/NAME.
I want to find out how ...
- 1
1
vote
1
answer
54
views
Implementing a query, two types of strategies
Tables have not been created yet, but to simplify there is a groups and an items tables. A group contains an item id (and a group id). And several groups may contain the same item id.
For instance
...
- 513
1
vote
2
answers
1k
views
Does the EXIST clause only return distinct rows by its nature?
I have two queries that appear to be logically equivalent, yet they return different result sets. I am using the AdventureWorks2012 database.
The first query uses an EXISTS clause with a subquery:
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- 311