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Does MongoDB's $in clause guarantee order
...sults
{ "$sort": { "weight": 1 } }
])
So that would be the expanded form. What basically happens here is that just as the array of values is passed to $in you also construct a "nested" $cond statement to test the values and assign an appropriate weight. As that "weight" value reflects the ord...
How to drop SQL default constraint without knowing its name?
...osoft SQL Server, I know the query to check if a default constraint exists for a column and drop a default constraint is:
1...
LAST_INSERT_ID() MySQL
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what if 2 INSERTS happend at the same time or one before another?
– FosAvance
Mar 28 '13 at 16:45
32
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MySQL ON DUPLICATE KEY - last insert id?
...bottom of the page they explain how you can make LAST_INSERT_ID meaningful for updates by passing an expression to that MySQL function.
From the MySQL documentation example:
If a table contains an AUTO_INCREMENT column and INSERT ... UPDATE inserts a row, the LAST_INSERT_ID() function returns t...
Schema for a multilanguage database
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What do you think about having a related translation table for each translatable table?
CREATE TABLE T_PRODUCT (pr_id int, PRICE NUMBER(18, 2))
CREATE TABLE T_PRODUCT_tr (pr_id INT FK, languagecode varchar, pr_name text, pr_descr text)
This way if you have multiple translatable col...
Overriding id on create in ActiveRecord
...of the database on every call, you just store your data in yml files. The foreign keys in the database reference the in-memory ids in the yml.
ActiveHash is great for picklists and small tables that change infrequently and only change by developers. So when going from ActiveHash to ActiveRecord, ...
Using LIMIT within GROUP BY to get N results per group?
..._in_set, you could then use this query that returns only the first 5 years for every id:
SELECT
yourtable.*
FROM
yourtable INNER JOIN (
SELECT
id,
GROUP_CONCAT(year ORDER BY rate DESC) grouped_year
FROM
yourtable
GROUP BY id) group_max
ON yourtable.id = group_max...
How to get next/previous record in MySQL?
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you're right, i forgot the FROM clause. thanks for pointing it out. :)
– longneck
Sep 20 '09 at 15:33
2
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How to create an object for a Django model with a many to many field?
...= Bar.objects.get(pk=2)
foo = Foo()
foo.save()
foo.bars = [bar1, bar2]
Unfortunately, that creates one additional SELECT:
SELECT "app_bar"."id", "app_bar"."name" FROM "app_bar" WHERE "app_bar"."id" = 1
SELECT "app_bar"."id", "app_bar"."name" FROM "app_bar" WHERE "app_bar"."id" = 2
INSERT INTO "ap...
Difference between “@id/” and “@+id/” in Android
...sely. I was having trouble finding the solution to this problem (or rather formulating the right search entry). I guess it might deserve a question+answer of its own.
– David Miler
Sep 24 '12 at 15:57
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