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Index on multiple columns in Ruby on Rails
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The order does matter in indexing.
Put the most selective field first, i.e. the field that narrows down the number of rows fastest.
The index will only be used insofar as you use its columns in sequence starting at the beginning. i.e. if you index on [:user_id, :article_id...
What is the difference between the Eclipse Package Explorer and the Eclipse Project Explorer?
...kage Explorer is it is the only explorer that appears in the list when you select "Show In" on a file that is being edited or has been found in the Search view.
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CSS text-overflow in a table cell?
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It messes up the selected width limits of every column, e.g. if you have some columns defined for max-width: X they now can be wider -- I thought this is because of display: flex being used, but I removed that and see no difference...
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Could not launch process launch failed: timed out waiting for app to launch
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Can I upload app in testflight via selecting developer certificate? Cause my app runs fine until I uploded to testflight and after uploding to testflight via distribution certificate this error is going to occur.
– Mrugesh Tank
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MySQL “incorrect string value” error when save unicode string in Django
...ASE `%s` CHARACTER SET 'utf8' COLLATE 'utf8_unicode_ci'" % dbname)
sql = "SELECT DISTINCT(table_name) FROM information_schema.columns WHERE table_schema = '%s'" % dbname
cursor.execute(sql)
results = cursor.fetchall()
for row in results:
sql = "ALTER TABLE `%s` convert to character set DEFAULT C...
How can I save a screenshot directly to a file in Windows? [closed]
...itmap!=IntPtr.Zero)
{
IntPtr hOld = (IntPtr) WIN32_API.SelectObject(hMemDC, m_HBitmap);
WIN32_API.BitBlt(hMemDC, 0, 0,size.cx,size.cy, hDC, 0, 0, WIN32_API.SRCCOPY);
WIN32_API.SelectObject(hMemDC, hOld);
WIN32_API.DeleteDC(hMemDC);
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How do I generate a random int number?
...SEED.This SEED is the beginning point, the trigger which instigates him to select the RANDOM value.
Now if a SEED is easy to guess then those kind of random numbers are termed as PSEUDO and when a seed is difficult to guess those random numbers are termed SECURED random numbers.
For example a perso...
Cannot insert explicit value for identity column in table 'table' when IDENTITY_INSERT is set to OFF
...need to generate the OperationID by yourself. The new id can be fetched by SELECT SCOPE_IDENTITY().
– Hakan Winther
Aug 26 '09 at 13:29
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Android Studio - Where can I see callstack while debugging an android app?
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At the bottom panel you should have "5: Debug". Click on it and select "Debugger -> Threads"
You may need to find the "Threads" icon on the far right, or even click the "Restore Layout" button on the left to restore this window.
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How to identify unused css definitions
...xtension Dust-Me at https://addons.mozilla.org/en-US/firefox/addon/dust-me-selectors/.
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