大约有 40,000 项符合查询结果（耗时：0.0165秒） [XML]
How to add column if not exists on PostgreSQL?
Question is simple. How to add column x to table y , but only when x column doesn't exist ? I found only solution here how to check if column exists.
...
Storing time-series data, relational or non?
... clause, it is very fast, and the query does not depend on the size of the table (grabbing 1,000 rows from a 16 billion row table is instantaneous).
Your table has one serious impediment. Given your description, the actual PK is (Device, Metric, DateTime). (Please don't call it TimeStamp, that mea...
Avoid duplicates in INSERT INTO SELECT query in SQL Server
I have the following two tables:
8 Answers
8
...
Getting the name of a child class in the parent class (static context)
...lt;?php
class Base
{
public static function find($id)
{
$table = static::$_table;
$class = static::getClass();
// $data = find_row_data_somehow($table, $id);
$data = array('table' => $table, 'id' => $id);
return new $class($data);
}
pu...
What's the recommended approach to resetting migration history using Django South?
...ion and fake-applies it (since your database already has the corresponding tables). There's no need to drop all the app tables during the process.
Here's what I'm doing on my dev + production server when I need to get rid of all these unneeded dev migrations:
Make sure we have the same DB sche...
SQL WHERE.. IN clause multiple columns
...
You can make a derived table from the subquery, and join table1 to this derived table:
select * from table1 LEFT JOIN
(
Select CM_PLAN_ID, Individual_ID
From CRM_VCM_CURRENT_LEAD_STATUS
Where Lead_Key = :_Lead_Key
) table2
ON
table1....
Wolfram's Rule 34 in XKCD [closed]
...using a Turing machine. The idea of a Turing machine is essentially that a table of data can be used to run computations on other data (i.e. a program is the first table and the input and output are the other table).
The first table (the program) gives rules that tell the machine what to do with th...
How to scroll to the bottom of a UITableView on the iPhone before the view appears
I have a UITableView that is populated with cells of a variable height. I would like the table to scroll to the bottom when the view is pushed into view.
...
Pretty Printing a pandas dataframe
How can I print a pandas dataframe as a nice text-based table, like the following?
9 Answers
...
Maximum number of records in a MySQL database table
What is the upper limit of records for MySQL database table. I'm wondering about autoincrement field. What would happen if I add milions of records? How to handle this kind of situations?
Thx!
...