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What's the difference between an exclusive lock and a shared lock?
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I wrote this answer down because I thought this would be a fun (and fitting) analogy:
Think of a lockable object as a blackboard (lockable) in a class room containing a teacher (writer) and many students (readers).
While a teacher is writing something (exclusive lock) on the board:
No...
How do I delete a fixed number of rows with sorting in PostgreSQL?
...'t change ctids, I don't think. Since that just compacts within each page, and the ctid is just the line number not a page offset. A VACUUM FULL or a CLUSTER operation would change the ctid, but those operations take an access exclusive lock on the table first.
– araqnid
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SELECT INTO using Oracle
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I though SELECT INTO was part of the Standard. Did Oracle do something strange here or was it never part of the standard?
– Robert Gould
Feb 12 '10 at 7:21
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LIKE vs CONTAINS on SQL Server
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The second (assuming you means CONTAINS, and actually put it in a valid query) should be faster, because it can use some form of index (in this case, a full text index). Of course, this form of query is only available if the column is in a full text index. If it isn...
How to make the 'cut' command treat same sequental delimiters as one?
...olumn-based, 'space'-adjusted text stream. I'm trying to use the cut command in the following manner:
5 Answers
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What is & used for
... character reference".
& is the character reference for "An ampersand".
&current; is not a standard character reference and so is an error (browsers may try to perform error recovery but you should not depend on this).
If you used a character reference for a real character (e.g. &...
Mock HttpContext.Current in Test Init Method
...xt itself is fakeable just enough for you do replace the IPrincipal (User) and IIdentity.
The following code runs as expected, even in a console application:
HttpContext.Current = new HttpContext(
new HttpRequest("", "http://tempuri.org", ""),
new HttpResponse(new StringWriter())
);
/...
Closing JDBC Connections in Pool
Our standard code section for using JDBC is...
3 Answers
3
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MySQL: Set user variable from result of query
...rator. However inside other statements, the assignment operator must be := and not = because = is treated as a comparison operator in non-SET statements.
UPDATE:
Further to comments below, you may also do the following:
SET @user := 123456;
SELECT `group` FROM user LIMIT 1 INTO @group;
SELECT ...
How to remove last n characters from every element in the R vector
I am very new to R, and I could not find a simple example online of how to remove the last n characters from every element of a vector (array?)
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