Opened by esskar at 2006-09-26 10:47
User since
2003-08-04
12209 Artikel
Admin1
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2003-08-04
12209 Artikel
Admin1
Code: (dl
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mysql> select * from a;
+------+------+
| a_id | name |
+------+------+
| 1 | foo |
| 2 | bar |
| 4 | baz |
+------+------+
3 rows in set (0.00 sec)
mysql> select * from b;
+------+--------------------+
| b_id | descr |
+------+--------------------+
| 2 | descr for bar |
| 3 | descr for whatever |
| 4 | descr for baz |
+------+--------------------+
3 rows in set (0.01 sec)
mysql> select * from a INNER JOIN b on a.a_id=b.b_id;
+------+------+------+---------------+
| a_id | name | b_id | descr |
+------+------+------+---------------+
| 2 | bar | 2 | descr for bar |
| 4 | baz | 4 | descr for baz |
+------+------+------+---------------+
2 rows in set (0.01 sec)
mysql> select * from a LEFT JOIN b on a.a_id=b.b_id;
+------+------+------+---------------+
| a_id | name | b_id | descr |
+------+------+------+---------------+
| 1 | foo | NULL | NULL |
| 2 | bar | 2 | descr for bar |
| 4 | baz | 4 | descr for baz |
+------+------+------+---------------+
3 rows in set (0.00 sec)
mysql> select * from a RIGHT JOIN b on a.a_id=b.b_id;
+------+------+------+--------------------+
| a_id | name | b_id | descr |
+------+------+------+--------------------+
| 2 | bar | 2 | descr for bar |
| NULL | NULL | 3 | descr for whatever |
| 4 | baz | 4 | descr for baz |
+------+------+------+--------------------+
3 rows in set (0.01 sec)
<!--EDIT|pq|1161350595-->
Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live. -- Damian Conway in "Perl Best Practices"
lesen:
Wie frage ich & perlintro brian's Leitfaden für jedes Perl-Problem
lesen:
Wie frage ich & perlintro brian's Leitfaden für jedes Perl-Problem