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Rails 3: Get Random Record
...You can use the following trick on an indexed column (PostgreSQL syntax):
select *
from my_table
where id >= trunc(
random() * (select max(id) from my_table) + 1
)
order by id
limit 1;
share
|
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MySQL: Selecting multiple fields into multiple variables in a stored procedure
Can I SELECT multiple columns into multiple variables within the same select query in MySQL?
3 Answers
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Setting JDK in Eclipse
...roperties the "JRE System Library" was still there. When I deleted it and selected "Use default Workspace JRE" only then did it pick up my change. I would have thought Eclipse should have updated my projects JRE when I selected a different JRE for my workspace
– MayoMan
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How to delete from select in MySQL?
...
SELECT (sub)queries return result sets. So you need to use IN, not = in your WHERE clause.
Additionally, as shown in this answer you cannot modify the same table from a subquery within the same query. However, you can either...
Counting the occurrences / frequency of array elements
... wider usage. Storing the values as object keys to count them means you're casting those values to strings and then counting that value. [5, "5"] will simply say you've got "5" two times. Or counting instances some different objects is just gonna tell you there's a lot of [object Object]. Etc. etc.
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Oracle SQL: Update a table with data from another table
...his is called a correlated update
UPDATE table1 t1
SET (name, desc) = (SELECT t2.name, t2.desc
FROM table2 t2
WHERE t1.id = t2.id)
WHERE EXISTS (
SELECT 1
FROM table2 t2
WHERE t1.id = t2.id )
Assuming the join results in a key-pr...
INSERT INTO…SELECT for all MySQL columns
... manual. Try this:
INSERT INTO this_table_archive (col1, col2, ..., coln)
SELECT col1, col2, ..., coln
FROM this_table
WHERE entry_date < '2011-01-01 00:00:00';
If the id columns is an auto-increment column and you already have some data in both tables then in some cases you may want to omit t...
Checking if an object is a given type in Swift
... able to do object.uppercaseString because the type of the variable is not casted to that type, you just checked that the object (pointed by the variable) is a String
– Ferran Maylinch
Jan 18 '17 at 16:53
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How does Bluebird's util.toFastProperties function make an object's properties “fast”?
...;IsJSObject()) {
JSObject::OptimizeAsPrototype(Handle<JSObject>::cast(value));
}
Which in turn is called by FuntionSetPrototype which is what we get with .prototype =.
Doing __proto__ = or .setPrototypeOf would have also worked but these are ES6 functions and Bluebird runs on all browsers...
Why does an overridden function in the derived class hide other overloads of the base class?
... interface. So maybe d->foo() won't get you the "Is-a Base", but static_cast<Base*>(d)->foo() will, including dynamic dispatch.
– Kerrek SB
Jan 9 '14 at 13:36
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