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What does SQL clause “GROUP BY 1” mean?
Someone sent me a SQL query where the GROUP BY clause consisted of the statement: GROUP BY 1 .
6 Answers
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How to drop a table if it exists?
...ver 2016+ has a better way, using DROP TABLE IF EXISTS …. See the answer by @Jovan.
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EF Code First: How do I see 'EntityValidationErrors' property from the nuget package console?
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I got annoyed by this recently too. I fixed it by putting a wrapper function in the Configuration class in the Seed method, and replaced calls to SaveChanges with calls to my function instead. This function would simply enumerate the err...
Explicit vs implicit SQL joins
...cting from 8 different tables and you have lots of filtering in the where. By using join syntax you separate out the parts where the tables are joined, to the part where you are filtering the rows.
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Difference between two lists
...(list2).ToList();
If you need to express a custom idea of equality, e.g. by ID, you'll need to implement IEqualityComparer<T>. For example:
public class IdComparer : IEqualityComparer<CustomObject>
{
public int GetHashCode(CustomObject co)
{
if (co == null)
{
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What do commas and spaces in multiple classes mean in CSS?
... I understand that we can apply one rule to several classes separated by comas. It's not clear to me why some classes in the example are not separated by commas.
– Roman
Jul 27 '10 at 13:53
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How do you make a LinearLayout scrollable?
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Here is how I did it by trial and error.
ScrollView - (the outer wrapper).
LinearLayout (child-1).
LinearLayout (child-1a).
LinearLayout (child-1b).
Since ScrollView can have only one child, that child is a linear layout...
Why there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT clause?
....',NULL);
NULL values for timestamp are interperted as CURRENT_TIMESTAMP by default.
In MySQL the first TIMESTAMP column of a table gets both DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP attribute, if no attributes are given for it.
this is why TIMESTAMP column with attributes must c...
How to get the last N records in mongodb?
I can't find anywhere it has been documented this. By default, the find() operation will get the records from beginning. How can I get the last N records in mongodb?
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How can I change the color of pagination dots of UIPageControl?
...or UIPageControl because that one only supports white dots.
//
// Created by Morten Heiberg <morten@heiberg.net> on November 1, 2010.
//
#import <UIKit/UIKit.h>
@protocol PageControlDelegate;
@interface PageControl : UIView
{
@private
NSInteger _currentPage;
NSInteger _numbe...