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Oracle: how to UPSERT (update or insert into a table?)
The UPSERT operation either updates or inserts a row in a table, depending if the table already has a row that matches the data:
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Efficiently convert rows to columns in sql server
...Code, LastName, AccountNumber
from
(
select value, columnname
from yourtable
) d
pivot
(
max(value)
for columnname in (Firstname, Amount, PostalCode, LastName, AccountNumber)
) piv;
See Demo.
Pivot with unknown number of columnnames
If you have an unknown number of columnnames that you w...
MySQL ON vs USING?
...fferences are noteworthy:
ON is the more general of the two. One can join tables ON a column, a set of columns and even a condition. For example:
SELECT * FROM world.City JOIN world.Country ON (City.CountryCode = Country.Code) WHERE ...
USING is useful when both tables share a column of the exac...
sqlite alter table add MULTIPLE columns in a single statement
Is it possible to alter table add MULTIPLE columns in a single statement in sqlite?
The following would not work.
4 Answers...
How do I find which transaction is causing a “Waiting for table metadata lock” state?
I am trying to perform some DDL on a table and SHOW PROCESSLIST results in a " Waiting for table metadata lock " message.
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UITableViewCell, show delete button on swipe
How do I get the delete button to show when swiping on a UITableViewCell ? The event is never raised and the delete button never appears.
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Having both a Created and Last Updated timestamp columns in MySQL 4.0
I have the following table schema;
11 Answers
11
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How To: Best way to draw table in console app (C#)
... of data changing in very fast intervals.
I want to display that data as a table in console app. f.ex:
12 Answers
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When and why are database joins expensive?
...nality when (if) they set up indexes.
It is important to understand that table scans (examination of every row in a table in the course of producing a join) are rare in practice. A query optimiser will choose a table scan only when one or more of the following holds.
There are fewer than 200 row...
Simple way to convert datarow array to datatable
I want to convert a DataRow array into DataTable ... What is the simplest way to do this?
14 Answers
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