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MongoDB SELECT COUNT GROUP BY
I am playing around with MongoDB trying to figure out how to do a simple
7 Answers
7
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Is there any difference between GROUP BY and DISTINCT
...CT and distinct by UNION cause an oracle error, but GROUP BY worked; I was selecting only 1 column from a view and not using any aggregation; I'm still baffled why it required it, but it does confirm there is some difference in the execution. As others point out, it also lets you GROUP BY columns no...
Convert a Scala list to a tuple?
... hence known at compile time. For example, (1,'a',true) has the type (Int, Char, Boolean), which is sugar for Tuple3[Int, Char, Boolean]. The reason tuples have this restriction is that they need to be able to handle a non-homogeneous types.
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SQL selecting rows by most recent date
...eturns a result set with ChargeId, ChargeType, and MostRecentServiceMonth
SELECT
CHARGEID,
CHARGETYPE,
MAX(SERVICEMONTH) AS "MostRecentServiceMonth"
FROM INVOICE
GROUP BY CHARGEID, CHARGETYPE
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Custom HTTP headers : naming conventions
...ed in section 2.2, 'Basic Rules'. Token is:
token = 1*<any CHAR except CTLs or separators>
In turn resting on CHAR, CTL and separators:
CHAR = <any US-ASCII character (octets 0 - 127)>
CTL = <any US-ASCII control character
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Entity Framework and SQL Server View
...mn as a primary key, use NULLIF.
An easy way to apply this is to wrap the select statement of your view in another select.
Example:
SELECT
ISNULL(MyPrimaryID,-999) MyPrimaryID,
NULLIF(AnotherProperty,'') AnotherProperty
FROM ( ... ) AS temp
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Want to find records with no associated records in Rails
... get everyone with no friends in the first case:
Person.where('id NOT IN (SELECT DISTINCT(person_id) FROM friends)')
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How can I insert values into a table, using a subquery with more than one result?
...
You want:
insert into prices (group, id, price)
select
7, articleId, 1.50
from article where name like 'ABC%';
where you just hardcode the constant fields.
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How to check if field is null or empty in MySQL?
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Either use
SELECT IF(field1 IS NULL or field1 = '', 'empty', field1) as field1
from tablename
or
SELECT case when field1 IS NULL or field1 = ''
then 'empty'
else field1
end as field1
from tablename
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Finding the type of an object in C++
... edited Jun 26 at 0:11
Richard Chambers
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answered Dec 9 '08 at 5:14
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