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When and why are database joins expensive?
...s back to mitigating the size of the working set. Joins involving properly selected keys with correctly set up indexes are cheap, not expensive, because they allow significant pruning of the result before the rows are materialised.
Materialising the result involves bulk disk reads which are the mo...
How to get a float result by dividing two integer values using T-SQL?
...s or parameters which are integers, you can cast them to be floats first:
SELECT CAST(1 AS float) / CAST(3 AS float)
or
SELECT CAST(MyIntField1 AS float) / CAST(MyIntField2 AS float)
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What is the difference between Left, Right, Outer and Inner Joins?
...ow you begin your query impacts the outcome of the join type. For example, SELECT * FROM students RIGHT OUTER JOIN lockers... would result in a different outcome than SELECT * FROM lockers RIGHT OUTER JOIN students.... Great answer, but would love to see it updated with complete SQL queries
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Can you use an alias in the WHERE clause in mysql?
...ts an unknown column. Is there any way to get around this issue? I need to select records that have a rating higher than x. Rating is calculated as the following alias:
...
Two single-column indexes vs one two-column index in MySQL?
... the statement I provided.
Additionally, MySQL can only use one index per SELECT so a covering index would be the best means of optimizing your queries.
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IIS Express Immediately shutting-down running site after stopping web application
...debugging is stopped.
Right click your project > click Properties > select the 'Web' tab on the left > uncheck the Enable Edit and Continue checkbox.
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How to combine class and ID in CSS selector?
...is is super old and people keep finding it: don't use the tagNames in your selectors. #content.myClass is faster than div#content.myClass because the tagName adds a filtering step that you don't need. Use tagNames in selectors only where you must!
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Is there a way to create xxhdpi, xhdpi, hdpi, mdpi and ldpi drawables from a large scale image?
...er:
To use it after installed, right click your res/drawable folder and select New > Batch Drawable Import:
Then select your image via the + button and set the Resolution to be xxhdpi (or whatever the resolution of your source image is).
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When should I use semicolons in SQL Server?
...llowing two queries (copied from this post):
BEGIN TRY
BEGIN TRAN
SELECT 1/0 AS CauseAnException
COMMIT
END TRY
BEGIN CATCH
SELECT ERROR_MESSAGE()
THROW
END CATCH
BEGIN TRY
BEGIN TRAN
SELECT 1/0 AS CauseAnException;
COMMIT
END TRY
BEGIN CATCH
SELECT ERROR_MES...
How to break lines at a specific character in Notepad++?
... + h or Search -> Replace on the top menu
Under the Search Mode group, select Regular expression
In the Find what text field, type ],\s*
In the Replace with text field, type ],\n
Click Replace All
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