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PostgreSQL DISTINCT ON with different ORDER BY
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Documentation says:
DISTINCT ON ( expression [, ...] ) keeps only the first row of each set of rows where the given expressions evaluate to equal. [...] Note that the "first row" of each set is unpredictable unless ORDER BY is used to ensure that th...
Postgres unique constraint vs index
As I can understand documentation the following definitions are equivalent:
8 Answers
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How do SQL EXISTS statements work?
I'm trying to learn SQL and am having a hard time understanding EXISTS statements. I came across this quote about "exists" and don't understand something:
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How to select where ID in Array Rails ActiveRecord without exception
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If it is just avoiding the exception you are worried about, the "find_all_by.." family of functions works without throwing exceptions.
Comment.find_all_by_id([2, 3, 5])
will work even if some of the ids don't exist. This works in the
user...
Passing an array to a query using a WHERE clause
...array(1,2,5) I want to have a SQL query that uses the values of the array in its WHERE clause like:
18 Answers
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Mysql order by specific ID values
Is it possible to sort in mysql by "order by" using predefined set of column values (ID) like: order by (ID=1,5,4,3) so I would get record 1, 5, 4, 3 in that order out?
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SQL server query to get the list of columns in a table along with Data types, NOT NULL, and PRIMARY
I need to write a query on SQL server to get the list of columns in a particular table, its associated data types (with length) and if they are not null. And I have managed to do this much.
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How to select html nodes by ID with jquery when the id contains a dot?
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@Tomalak in comments:
since ID selectors must be preceded by a hash #, there should be no ambiguity here
“#id.class” is a valid selector that requires both an id and a separate class to match; it's valid and not always total...
Bold words in a string of strings.xml in Android
I have a long text in one of the strings at strings.xml. I want to make bold and change the color of some words in that text.
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MySQL ON DUPLICATE KEY - last insert id?
I have the following query:
7 Answers
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