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Difference between Select Unique and Select Distinct
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SELECT UNIQUE is old syntax supported by Oracle's flavor of SQL. It is synonymous with SELECT DISTINCT.
Use SELECT DISTINCT because this is standard SQL, and SELECT UNIQUE is non-standard, and in database brands other than ...
Rails: select unique values from a column
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Model.select(:rating)
Result of this is a collection of Model objects. Not plain ratings. And from uniq's point of view, they are completely different. You can use this:
Model.select(:rating).map(&:rating).uniq
or this (mo...
How do you join on the same table, twice, in mysql?
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you'd use another join, something along these lines:
SELECT toD.dom_url AS ToURL,
fromD.dom_url AS FromUrl,
rvw.*
FROM reviews AS rvw
LEFT JOIN domain AS toD
ON toD.Dom_ID = rvw.rev_dom_for
LEFT JOIN domain AS fromD
ON fromD.Dom_ID = rvw.rev_dom_from
ED...
Can overridden methods differ in return type?
... class Alpha {
Alpha doStuff(char c) {
return new Alpha();
}
}
class Beta extends Alpha {
Beta doStuff(char c) { // legal override in Java 1.5
return new Beta...
How do you list the primary key of a SQL Server table?
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SELECT Col.Column_Name from
INFORMATION_SCHEMA.TABLE_CONSTRAINTS Tab,
INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE Col
WHERE
Col.Constraint_Name = Tab.Constraint_Name
AND Col.Table_Name = Tab.Table_Name
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How can I get column names from a table in Oracle?
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You can query the USER_TAB_COLUMNS table for table column metadata.
SELECT table_name, column_name, data_type, data_length
FROM USER_TAB_COLUMNS
WHERE table_name = 'MYTABLE'
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Import / Export database with SQL Server Server Management Studio
... if you want to also export the data, on the "Set Scripting Options" step, select the "Advanced" button and change "Types of data to script" from "Schema Only" to "Data Only" or "Schema and Data".
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Command line progress bar in Java
...plemented this sort of thing before. Its not so much about java, but what characters to send to the console.
The key is the difference between \n and \r.
\n goes to the start of a new line. But \r is just carriage return - it goes back to the start of the same line.
So the thing to do is to prin...
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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How to do SELECT COUNT(*) GROUP BY and ORDER BY in Django?
...lvaro has answered the Django's direct equivalent for GROUP BY statement:
SELECT actor, COUNT(*) AS total
FROM Transaction
GROUP BY actor
is through the use of values() and annotate() methods as follows:
Transaction.objects.values('actor').annotate(total=Count('actor')).order_by()
However ...