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How to concatenate strings of a string field in a PostgreSQL 'group by' query?
...e
GROUP BY company_id;
Postgres 9.0 also added the ability to specify an ORDER BY clause in any aggregate expression; otherwise, the order is undefined. So you can now write:
SELECT company_id, string_agg(employee, ', ' ORDER BY employee)
FROM mytable
GROUP BY company_id;
Or indeed:
SELECT str...
How to select only 1 row from oracle sql?
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@bdares: it will work, yes. But not your answer, with the order by.
– ypercubeᵀᴹ
Jan 19 '12 at 0:30
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Is a Python list guaranteed to have its elements stay in the order they are inserted in?
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Yes, the order of elements in a python list is persistent.
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Sorting arrays in NumPy by column
... actually the most elegant way of doing it.
For the "correct" way see the order keyword argument of numpy.ndarray.sort
However, you'll need to view your array as an array with fields (a structured array).
The "correct" way is quite ugly if you didn't initially define your array with fields...
A...
How are Python's Built In Dictionaries Implemented?
...dom probing. In random probing, the next slot is picked in a pseudo random order. The entry is added to the first empty slot. For this discussion, the actual algorithm used to pick the next slot is not really important (see dictobject.c:33-126 for the algorithm for probing). What is important is tha...
How to pull a random record using Django's ORM?
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Using order_by('?') will kill the db server on the second day in production. A better way is something like what is described in Getting a random row from a relational database.
from django.db.models.aggregates import Count
from r...
In Python, when to use a Dictionary, List or Set?
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A list keeps order, dict and set don't: when you care about order, therefore, you must use list (if your choice of containers is limited to these three, of course;-).
dict associates with each key a value, while list and set just contain...
selecting unique values from a column
...se the DISTINCT operator in MySQL:
SELECT DISTINCT(Date) AS Date FROM buy ORDER BY Date DESC;
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Are PDO prepared statements sufficient to prevent SQL injection?
...statements / parameterized queries are generally sufficient to prevent 1st order injection on that statement*. If you use un-checked dynamic sql anywhere else in your application you are still vulnerable to 2nd order injection.
2nd order injection means data has been cycled through the database on...
How to make ng-repeat filter out duplicate results
...nd use it directly in the ng-options (or ng-repeat).
<select ng-model="orderProp" ng-options="place.category for place in places | unique:'category'">
<option value="0">Default</option>
// unique options from the categories
</select>
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