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How can I select rows with most recent timestamp for each key value?
...r data. Each row has a sensor id, a timestamp, and other fields. I want to select a single row with latest timestamp for each sensor, including some of the other fields.
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How to delete duplicates on a MySQL table?
...n an index is going to be slow for large tables. Wouldn't it be better to SELECT MAX(ID) FROM t GROUP BY unique and then JOIN to an exact match of ID to MAX(ID)?
– ebyrob
Nov 10 '16 at 16:31
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How to Join to first row
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SELECT Orders.OrderNumber, LineItems.Quantity, LineItems.Description
FROM Orders
JOIN LineItems
ON LineItems.LineItemGUID =
(
SELECT TOP 1 LineItemGUID
FROM LineItems
W...
How to use Checkbox inside Select Option
The client has given me a design which has a Select Option menu containing a checkbox together with the item name as individual items in the list.
Is there anyway possible to add a checkbox inside a Select Option menu?
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Evaluating a mathematical expression in a string
...low, I've rewrapped fourFn into a numeric parser class for easier reuse.
from __future__ import division
from pyparsing import (Literal, CaselessLiteral, Word, Combine, Group, Optional,
ZeroOrMore, Forward, nums, alphas, oneOf)
import math
import operator
__author__ = 'Paul...
jQuery UI Tabs - How to Get Currently Selected Tab Index
...answer is there - use ui.index property to get the current index in the tabselect event.....
– redsquare
Nov 5 '09 at 12:27
17
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How does the ThreadStatic attribute work?
...e attribute on an inappropriate (non-static) symbol doesn't get a reaction from the compiler. The compiler doesn't know what special semantics the attribute requires. Code analysis tools like FX/Cop, though, should know about it.
Another way to look at it: CIL defines a set of storage scopes: st...
Fastest way to determine if record exists
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SELECT TOP 1 products.id FROM products WHERE products.id = ?; will outperform all of your suggestions as it will terminate execution after it finds the first record.
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SQL join: selecting the last records in a one-to-many relationship
... want to get a list of all customers along with their last purchase in one SELECT statement. What is the best practice? Any advice on building indexes?
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Removing duplicate rows from table in Oracle
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Use the rowid pseudocolumn.
DELETE FROM your_table
WHERE rowid not in
(SELECT MIN(rowid)
FROM your_table
GROUP BY column1, column2, column3);
Where column1, column2, and column3 make up the identifying key for each record. You might list all your columns.
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