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Finding duplicate rows in SQL Server
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select o.orgName, oc.dupeCount, o.id
from organizations o
inner join (
SELECT orgName, COUNT(*) AS dupeCount
FROM organizations
GROUP BY orgName
HAVING COUNT(*) > 1
) oc on o.orgName = oc.orgName
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When to add what indexes in a table in Rails
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Should I add "index" to all the foreign keys like "xxx_id"?
It would be better, because it accelerates the search in sorting in this column. And Foreign keys are something searched for a lot.
Since Version 5 of rails the index will be c...
How to get multiple counts with one SQL query?
I am wondering how to write this query.
9 Answers
9
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LINQ - Full Outer Join
... a first name and some don't have a surname; I'd like to do a full outer join on the two lists.
16 Answers
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SQL JOIN and different types of JOINs
What is a SQL JOIN and what are different types?
6 Answers
6
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Exposing database IDs - security risk?
I've heard that exposing database IDs (in URLs, for example) is a security risk, but I'm having trouble understanding why.
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How to remove item from list in C#?
I have a list stored in resultlist as follows:
8 Answers
8
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What is the meaning of id?
I am (trying to) learn Objective-C and I keep coming across a phrase like:
5 Answers
5...
How to delete from select in MySQL?
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SELECT (sub)queries return result sets. So you need to use IN, not = in your WHERE clause.
Additionally, as shown in this answer you cannot modify the same table from a subquery within the same query. However, you can either SELECT then DELETE in separate queries, or nest another su...
Mysql error 1452 - Cannot add or update a child row: a foreign key constraint fails
I'm having a bit of a strange problem. I'm trying to add a foreign key to one table that references another, but it is failing for some reason. With my limited knowledge of MySQL, the only thing that could possibly be suspect is that there is a foreign key on a different table referencing the one I ...