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Does a foreign key automatically create an index?
I've been told that if I foreign key two tables, that SQL Server will create something akin to an index in the child table. I have a hard time believing this to be true, but can't find much out there related specifically to this.
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Why would someone use WHERE 1=1 AND in a SQL clause?
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Indirectly Relevant: when 1=2 is used:
CREATE TABLE New_table_name
as
select *
FROM Old_table_name
WHERE 1 = 2;
this will create a new table with same schema as old table. (Very handy if you want to load some data for compares)
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Finding duplicate values in MySQL
I have a table with a varchar column, and I would like to find all the records that have duplicate values in this column. What is the best query I can use to find the duplicates?
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What are the differences between virtual memory and physical memory?
...perating system creates and deals with these mappings - utilizing the page table, among other data structures to maintain the mappings. Virtual memory mappings are always found in the page table or some similar data structure (in case of other implementations of virtual memory, we maybe shouldn't ca...
Custom UITableViewCell from nib in Swift
I'm trying to create a custom table view cell from a nib. I'm referring to this article here . I'm facing two issues.
11 A...
How to delete a certain row from mysql table with same column values?
I have a problem with my queries in MySQL. My table has 4 columns and it looks something like this:
6 Answers
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Remove Trailing Spaces and Update in Columns in SQL Server
I have trailing spaces in a column in a SQL Server table called Company Name .
13 Answers
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How to delete all records from table in sqlite with Android?
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You missed a space: db.execSQL("delete * from " + TABLE_NAME);
Also there is no need to even include *, the correct query is:
db.execSQL("delete from "+ TABLE_NAME);
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There can be only one auto column
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My MySQL says "Incorrect table definition; there can be only one auto column and it must be defined as a key" So when I added primary key as below it started working:
CREATE TABLE book (
id INT AUTO_INCREMENT NOT NULL,
accepted_terms BIT(1) NO...
How is set() implemented?
...zation(s) that exploit this lack of values
So basically a set uses a hashtable as its underlying data structure. This explains the O(1) membership checking, since looking up an item in a hashtable is an O(1) operation, on average.
If you are so inclined you can even browse the CPython source code...