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How many database indexes is too many?
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It depends on the operations that occur on the table.
If there's lots of SELECTs and very few changes, index all you like.... these will (potentially) speed the SELECT statements up.
If the table is heavily hit by UPDATEs, INSERTs + DELETEs ... these will be very slow with lots of indexes since t...
Is it possible to GROUP BY multiple columns using MySQL?
Is it possible to GROUP BY more than one column in a MySQL SELECT query? For example:
7 Answers
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Hidden Features of MySQL
...that has an integer type,
you can also refer to the column as "_rowid" in SELECT statements.
In MySQL, the name of a PRIMARY KEY is PRIMARY
Currently, only InnoDB (v5.1?) tables support foreign keys.
Usually, you create all the indexes you need when you are creating tables.
Any column declared...
Xcode “Build and Archive” from command line
... in Xcode 4.4, and I'm sure it was fine in 4.3 as well. Make sure you have selected the correct Xcode release by using xcode-select <path to Xcode.app>
– Reid Ellis
Jul 30 '12 at 18:02
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Is there an easy way to attach source in Eclipse?
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Go to Properties (for the Project) -> Java Build Path -> Libraries
Select the Library you want to attach source/javadoc for and then expand it, you'll see a list like so:
Source Attachment: (none)
Javadoc location: (none)
Native library location: (none)
Access rules: (No restrictions)
Sel...
How to disable UITextField editing but still accept touch?
... inputView . Its all good, except that I can edit by copy, paste, cut and select text, and I don't want it. Only the Picker should modify text field.
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Input widths on Bootstrap 3
Update again: I am closing this question by selecting the top answer to keep people from adding answers without really understanding the question. In reality there is no way to do it with the build in functionality without using grid or adding extra css. Grids do not work well if you are dealing wi...
string.Join on a List or other type
...le<T>)
If you can't upgrade, you can achieve the same effect using Select and ToArray.
return string.Join(",", a.Select(x => x.ToString()).ToArray());
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Best way to work with transactions in MS SQL Server Management Studio
...FROM Production.Product
WHERE ProductID = 980;
END TRY
BEGIN CATCH
SELECT
ERROR_NUMBER() AS ErrorNumber
,ERROR_SEVERITY() AS ErrorSeverity
,ERROR_STATE() AS ErrorState
,ERROR_PROCEDURE() AS ErrorProcedure
,ERROR_LINE() AS ErrorLine
,ERROR_MESS...
How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...and re-try where necessary.
Some attempted solutions also fail to consider SELECT races. If you try the obvious and simple:
-- THIS IS WRONG. DO NOT COPY IT. It's an EXAMPLE.
BEGIN;
UPDATE testtable
SET somedata = 'blah'
WHERE id = 2;
-- Remember, this is WRONG. Do NOT COPY IT.
INSERT INTO testt...