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SQL JOIN - WHERE clause vs. ON clause
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They are not the same thing.
Consider these queries:
SELECT *
FROM Orders
LEFT JOIN OrderLines ON OrderLines.OrderID=Orders.ID
WHERE Orders.ID = 12345
and
SELECT *
FROM Orders
LEFT JOIN OrderLines ON OrderLines.OrderID=Orders.ID
AND Orders.ID = 12345
The first will re...
How to get ERD diagram for an existing database?
...t that up in Manage, in which case all your databases will be available to select in step 3)
Import all objects (it will warn that you are importing to the current model, which is fine since it is empty).
Now switch back to the Design tab to see your ERD.
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Regex match everything after question mark?
... for something like this? Topics: code, programming, design So I want to select the colon and look behind as far as the cpaital T of topics and fowards to the end on the line? (in this case end of the line is "design".
– Mark
Dec 11 '10 at 21:36
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Error “The connection to adb is down, and a severe error has occurred.”
... I solved my issue. I go to Task Manager in windows7 -> processes -> selected the adb.exe -> End Process. After that I go to cmd prompt and type adb start-server. This time adb statred succefully. I run eclipe and it was showing no error.
– Nishant
Apr...
MySQL: Transactions vs Locking Tables
...ransactions vs locking tables to ensure database integrity and make sure a SELECT and UPDATE remain in sync and no other connection interferes with it. I need to:
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updating table rows in postgres using subquery
...ery.customer,
address=subquery.address,
partn=subquery.partn
FROM (SELECT address_id, customer, address, partn
FROM /* big hairy SQL */ ...) AS subquery
WHERE dummy.address_id=subquery.address_id;
This syntax is not standard SQL, but it is much more convenient for this type of query...
Overriding a Rails default_scope
...ed_at desc')
end
Foo.reorder('created_at asc')
runs the following SQL:
SELECT * FROM "foos" ORDER BY created_at asc
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Python: Select subset from list based on index set
...ecause this will be very familiar syntax to users of R, where this kind of selection is very powerful, especially when nested and/or multidimensional.
– Thomas Browne
May 25 '14 at 21:11
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What's the difference between NOT EXISTS vs. NOT IN vs. LEFT JOIN WHERE IS NULL?
... using Standard SQL.
An obvious omission is the equivalent using EXCEPT:
SELECT a FROM table1
EXCEPT
SELECT a FROM table2
Note in Oracle you need to use the MINUS operator (arguably a better name):
SELECT a FROM table1
MINUS
SELECT a FROM table2
Speaking of proprietary syntax, there may also ...
UITapGestureRecognizer breaks UITableView didSelectRowAtIndexPath
...ch.view isDescendantOfView:autocompleteTableView]) {
// Don't let selections of auto-complete entries fire the
// gesture recognizer
return NO;
}
return YES;
}
That took care of it. Hopefully this will help others as well.
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