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How to include “zero” / “0” results in COUNT aggregate?
...n outer join for this (and you need to use person as the "driving" table)
SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM person
LEFT JOIN appointment ON person.person_id = appointment.person_id
GROUP BY person.person_id;
The reason why this is working, i...
Swapping column values in MySQL
...rows affected (0.08 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM swaptest;
+------+------+
| X | Y |
+------+------+
| 1 | 2 |
| 3 | 4 |
| -5 | -8 |
| -13 | 27 |
+------+------+
4 rows in set (0.00 sec)
mysql>
Here is the swap being performed
m...
Which version of PostgreSQL am I running?
...
Run this query from PostgreSQL:
SELECT version();
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Maximum Year in Expiry Date of Credit Card
...orget that in most browsers you can still key in the number and it'll auto select.
– Kevin Wiskia
Mar 22 '11 at 19:44
1
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Spring JPA selecting specific columns
...Spring JPA to perform all database operations. However I don't know how to select specific columns from a table in Spring JPA?
...
How to detect Ctrl+V, Ctrl+C using JavaScript?
... Dude! Thanks! This is exactly what I needed to enable users to select an "element" (calendar entry) in a web app I'm writing, hit ctrl + c to "copy" it, then ctrl+v to "paste" it, all without actually interacting with the allmighty blessed clipboard. ctrl+c I remember what they're clicke...
Java: Subpackage visibility?
...rotected byte[] getDataAsBytes(){ return data.getBytes(); }
protected char[] getDataAsChars(){ return data.toCharArray(); }
}
make a class in that package that overrides the methods you need in ClassInA:
package a.b;
import a.ClassInA;
public class ClassInAInB extends ClassInA{
ClassIn...
sed error: “invalid reference \1 on `s' command's RHS”
...
Sorry. The edit raises the error: sed: -e expression #7, char 58: Invalid range end. @Denis' answer works.
– JJD
May 19 '13 at 18:29
...
Core dumped, but core file is not in the current directory?
...ore_pattern is used to specify a core dumpfile pattern name.
If the first character of the pattern is a '|', the kernel will treat
the rest of the pattern as a command to run. The core dump will be
written to the standard input of that program instead of to a file.
Instead of writing the core du...
The Ruby %r{ } expression
...y, for legibility.
Edit:
Note that you can use almost any non-alphabetic character pair instead of '{}'.
These variants work just as well:
%r!/home/user!
%r'/home/user'
%r(/home/user)
Edit 2:
Note that the %r{}x variant ignores whitespace, making complex regexps more readable. Example from Git...