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Finding duplicate values in a SQL table
...T(*) > 1
Simply group on both of the columns.
Note: the older ANSI standard is to have all non-aggregated columns in the GROUP BY but this has changed with the idea of "functional dependency":
In relational database theory, a functional dependency is a constraint between two sets of attrib...
What's the difference between Unicode and UTF-8? [duplicate]
...uses UTF-16LE encoding internally as the memory storage format for Unicode strings, it considers this to be the natural encoding of Unicode text. In the Windows world, there are ANSI strings (the system codepage on the current machine, subject to total unportability) and there are Unicode strings (s...
Find all records which have a count of an association greater than zero
... Well that is Rails for you. If you can provide an sql answer (and explain why this isn't efficient), that may be a lot more helpful.
– jvnill
May 7 '19 at 23:17
...
Delete with Join in MySQL
...oject_id
WHERE projects.client_id = :client_id
In this case, table_name1 and table_name2 are the same table, so this will work:
DELETE projects FROM posts INNER JOIN [...]
You can even delete from both tables if you wanted to:
DELETE posts, projects FROM posts INNER JOIN [...]
Note that orde...
Drop columns whose name contains a specific string from pandas DataFrame
...er, and Idiomatic: str.contains
In recent versions of pandas, you can use string methods on the index and columns. Here, str.startswith seems like a good fit.
To remove all columns starting with a given substring:
df.columns.str.startswith('Test')
# array([ True, False, False, False])
df.loc[:,~...
How to properly create composite primary keys - MYSQL
... gross oversimplification of an intense setup I am working with. table_1 and table_2 both have auto-increment surrogate primary keys as the ID. info is a table that contains information about both table_1 and table_2 .
...
Different results with Java's digest versus external utilities
... Main()
{
using (var md5 = MD5.Create())
{
string path = "c:/Windows/System32/Calc.exe";
var bytes = md5.ComputeHash(File.ReadAllBytes(path));
Console.WriteLine(BitConverter.ToString(bytes));
}
}
}
And here's a console session (mi...
Deserialize json object into dynamic object using Json.net
...n.NET allows us to do this:
dynamic d = JObject.Parse("{number:1000, str:'string', array: [1,2,3,4,5,6]}");
Console.WriteLine(d.number);
Console.WriteLine(d.str);
Console.WriteLine(d.array.Count);
Output:
1000
string
6
Documentation here: LINQ to JSON with Json.NET
See also JObject.Parse ...
SQL JOIN and different types of JOINs
What is a SQL JOIN and what are different types?
6 Answers
6
...
How do you make a WPF slider snap only to discrete integer positions?
... will show decimals. If you also bind to an int at the same time the empty string will cause a conversion exception to be thrown that briefly bogs down the UI. These issues haven't been severe enough for me to look for solutions.
...