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count(*) vs count(column-name) - which is more correct? [duplicate]
... null.
Therefore COUNT(*) is what you should use. If you're using MyISAM and there is no WHERE clause, then the optimiser doesn't even have to look at the table, since the number of rows is already cached.
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How to check if anonymous object has a method?
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Doesn't handle the case where the property is defined, but is not a function.
– matt2000
Aug 29 '18 at 23:42
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Linq select objects in list where exists IN (A,B,C)
...ad of array for allowedStatus because HashSet's contains method is fastest and there'll be performance issues with array if it contains more than 1000 items. var allowedStatus = new HashSet<string> { "A", "B", "C" };
– Jay Shah
Nov 9 '18 at 18:14
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How to randomly select an item from a list?
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Use random.choice()
import random
foo = ['a', 'b', 'c', 'd', 'e']
print(random.choice(foo))
For cryptographically secure random choices (e.g. for generating a passphrase from a wordlist) use secrets.choice()
import secrets
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“FOUNDATION_EXPORT” vs “extern”
...ill see that FOUNDATION_EXPORT compiles to extern in C, extern "C" in C++, and other things in Win32. So, it's more compatible across languages and operating systems. For many projects, this won't make any difference.
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Set value to NULL in MySQL
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You're probably quoting 'NULL'. NULL is a reserved word in MySQL, and can be inserted/updated without quotes:
INSERT INTO user (name, something_optional) VALUES ("Joe", NULL);
UPDATE user SET something_optional = NULL;
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z-index not working with position absolute
I opened the console (chrome\firefox) and ran the following lines:
5 Answers
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Custom attributes in styles.xml
I have created a custom widget, and I'm declaring it in layout.xml. I have also added some custom attributes in attr.xml. However, when trying to declare these attributes in a style in styles.xml, it's giving me No resource found that matches the given name: attr 'custom:attribute'.
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Clear form field after select for jQuery UI Autocomplete
I'm developing a form, and using jQuery UI Autocomplete. When the user selects an option, I want the selection to pop into a span appended to the parent <p> tag. Then I want the field to clear rather than be populated with the selection.
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Reload django object from database
...@Yunti You can defer fields, or explicitly ask for only a subset of fields and the resulting object will be only partially populated. refresh_from_db will only update such already populated fields.
– 301_Moved_Permanently
Jan 16 '19 at 16:37
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