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In which scenario do I use a particular STL container?
...
You now have unordered_map and unordered_set (and their multi variants) which are not in the flow chart but are good picks when you don't care about order but need to find elements by key. Their lookup is usually O(1) instead of O(log n).
...
Optimal way to concatenate/aggregate strings
...LECT
ID,
Name,
ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Name) AS NameNumber,
COUNT(*) OVER (PARTITION BY ID) AS NameCount
FROM dbo.SourceTable
),
Concatenated AS
(
SELECT
ID,
CAST(Name AS nvarchar) AS FullName,
Name,
Nam...
SQL Server CTE and recursion example
...loyees
WHERE EmployeeID = cteReports.MgrID) AS Manager
FROM cteReports
ORDER BY EmpLevel, MgrID
The simplest example of a recursive CTE I can think of to illustrate its operation is;
;WITH Numbers AS
(
SELECT n = 1
UNION ALL
SELECT n + 1
FROM Numbers
WHERE n+1 <= 10
)
S...
Why use make over a shell script?
... other sort of tree analysis that determines what depends on what and what order to build the out-of-date things such that every prerequisite is built before every dependency, and only built once.
It's a language for declarative programming. New elements can be added without needing to merge them in...
What's the difference between UTF-8 and UTF-8 without BOM?
...t use a BOM or where the BOM is used as a UTF-8 signature. See the “Byte Order Mark” subsection in Section 16.8, Specials, for more information.
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Remove duplicate rows in MySQL
...owing columns:
employee (id, first_name, last_name, start_date, ssn)
In order to delete the rows with a duplicate ssn column, and keeping only the first entry found, the following process can be followed:
-- create a new tmp_eployee table
CREATE TABLE tmp_employee LIKE employee;
-- add a unique...
Java 8 stream reverse order
...tores the elements into an array and reads them out to a stream in reverse order. Note that since we don't know the runtime type of the stream elements, we can't type the array properly, requiring an unchecked cast.
@SuppressWarnings("unchecked")
static <T> Stream<T> reverse(Stream<T...
How do I delete a fixed number of rows with sorting in PostgreSQL?
...DELETE FROM logtable
WHERE ctid IN (
SELECT ctid
FROM logtable
ORDER BY timestamp
LIMIT 10
)
The ctid is:
The physical location of the row version within its table. Note that although the ctid can be used to locate the row version very quickly, a row's ctid will change if it is...
DataContractSerializer doesn't call my constructor?
...But the XmlSerializer also needs public getter and setter on properties in order to serialize / deserialize.
I think of the DataContractSerializer / BinaryFormatter behavior like suspending the state of an instance during serialization and resuming during deserialization. In other words, the insta...
How does a hash table work?
...
Each bucket can have multiple records which are organized in a particular order.
Real World Example:
Hash & Co., founded in 1803 and lacking any computer technology had a total of 300 filing cabinets to keep the detailed information (the records) for their approximately 30,000 clients. Each...