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How do I add a foreign key to an existing SQLite table?
...n step 8 below. One way to
do this is to run a query like the following: SELECT type, sql FROM
sqlite_master WHERE tbl_name='X'.
Use CREATE TABLE to construct a new table "new_X" that is in the
desired revised format of table X. Make sure that the name "new_X"
does not collide with any exi...
Select Last Row in the Table
I would like to retrieve the last file inserted into my table. I know that the method first() exists and provides you with the first file in the table but I don't know how to get the last insert.
...
Select between two dates with Django
I am looking to make a query that selects between dates with Django.
4 Answers
4
...
Android Studio says “cannot resolve symbol” but project compiles
...y only thought so far: right click the jar file in file tree within AS and select "Add as library..."
EDIT: You can do "File" -> "Invalidate Caches...", and select "Invalidate and Restart" option to fix this.
EDIT 2: This fix should work for all similar incidents and is not a twitter4j specific...
Images can't contain alpha channels or transparencies
...rt to PNG without alpha in Preview. Simply open your image, choose export, select PNG, uncheck Alpha, and click Save. Preview also support batch export if you open all your images at once.
– Russell Ladd
Jan 7 '15 at 6:23
...
How to select the row with the maximum value in each group
In a dataset with multiple observations for each subject I want to take a subset with only the maximum data value for each record. For example, with a following dataset:
...
How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
... 0.0 NaN 0.0
3 0.0 1.0 2.0 3.0
4 NaN 0.0 NaN NaN
If you want to select the rows that have two or more columns with null value, you run the following:
>>> qty_of_nuls = 2
>>> df.iloc[df[(df.isnull().sum(axis=1) >=qty_of_nuls)].index]
0 1 2 3
1 0.0 NaN 0...
Use LINQ to get items in one List, that are not in another List
...erride the equality:
var excludedIDs = new HashSet<int>(peopleList1.Select(p => p.ID));
var result = peopleList2.Where(p => !excludedIDs.Contains(p.ID));
This variant does not remove duplicates.
share
...
Convert an image (selected by path) to base64 string
How do you convert an image from a path on the user's computer to a base64 string in C#?
12 Answers
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What are C++ functors and their uses?
...te:
class SomeClass
{
std::string state_;
public:
SomeClass(const char* s) : state_(s) {}
void method( std::string param )
{
std::cout << state_ << param << std::endl;
}
};
SomeClass *inst = new SomeClass("Hi, i am ");
boost::function< void (std::st...