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How can I create and style a div using JavaScript?
...
var div = document.createElement("div");
div.style.width = "100px";
div.style.height = "100px";
div.style.background = "red";
div.style.color = "white";
div.innerHTML = "Hello";
document.getElementById("main").appendChild(div);
<body>
<div id="main"></d...
How can I SELECT rows with MAX(Column value), DISTINCT by another column in SQL?
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@Young the problem with your query is that it may return id, player and resource of non-max row for a given home i.e. for home = 10 you may get : 3 | 10 | 04/03/2009 | john | 300 In other words it doesn't guarantees that all column of a row in resultset will belong to max(da...
What's the $unwind operator in MongoDB?
...f adding and obtaining the data from your storage locations.
That being said, in order to understand the concept behind the $unwind parameter, you first must understand what the use case that you are trying to quote is saying. The example document from mongodb.org is as follows:
{
title : "this i...
PostgreSQL Autoincrement
...
Yes, SERIAL is the equivalent function.
CREATE TABLE foo (
id SERIAL,
bar varchar);
INSERT INTO foo (bar) values ('blah');
INSERT INTO foo (bar) values ('blah');
SELECT * FROM foo;
1,blah
2,blah
SERIAL is just a create table time macro around sequences. You can not alter SERIAL...
Check if table exists and if it doesn't exist, create it in SQL Server 2008
...mething like this
IF NOT EXISTS (SELECT * FROM sys.objects
WHERE object_id = OBJECT_ID(N'[dbo].[YourTable]') AND type in (N'U'))
BEGIN
CREATE TABLE [dbo].[YourTable](
....
....
....
)
END
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How to use NSJSONSerialization
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Your root json object is not a dictionary but an array:
[{"id": "1", "name":"Aaa"}, {"id": "2", "name":"Bbb"}]
This might give you a clear picture of how to handle it:
NSError *e = nil;
NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutabl...
UPDATE multiple tables in MySQL using LEFT JOIN
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UPDATE t1
LEFT JOIN
t2
ON t2.id = t1.id
SET t1.col1 = newvalue
WHERE t2.id IS NULL
Note that for a SELECT it would be more efficient to use NOT IN / NOT EXISTS syntax:
SELECT t1.*
FROM t1
WHERE t1.id NOT IN
(
SELECT id
...
What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
...:
SELECT * FROM Cars;
And then for each Car:
SELECT * FROM Wheel WHERE CarId = ?
In other words, you have one select for the Cars, and then N additional selects, where N is the total number of cars.
Alternatively, one could get all wheels and perform the lookups in memory:
SELECT * FROM Wheel
Thi...
Best way to select random rows PostgreSQL
...pecifications (plus additional info in the comments),
You have a numeric ID column (integer numbers) with only few (or moderately few) gaps.
Obviously no or few write operations.
Your ID column has to be indexed! A primary key serves nicely.
The query below does not need a sequential scan of the...
How to sort with lambda in Python
...reverse=False)
so without the key=, the function you pass in will be considered a cmp function which takes 2 arguments.
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