大约有 7,000 项符合查询结果（耗时：0.0354秒） [XML]
What is __init__.py for?
...ABASE URL'? I tried to replicate this by enclosing the create_engine with 'mysql+mysqldb://root:python@localhost:3306/test' but it does not work. Thanks.
– SunnyBoiz
Jun 25 '19 at 13:34
...
How to generate .json file with PHP?
...t * from Posts limit 20";
$response = array();
$posts = array();
$result=mysql_query($sql);
while($row=mysql_fetch_array($result)) {
$title=$row['title'];
$url=$row['url'];
$posts[] = array('title'=> $title, 'url'=> $url);
}
$response['posts'] = $posts;
$fp = fopen('results.json...
SQL update query using joins
...
FYI this will NOT work in MySQL (different syntax)! For MySQL have a look at gcbenison's answer
– Sliq
Jan 17 '17 at 16:28
...
How can I use UUIDs in SQLAlchemy?
...nally got it solid.
from sqlalchemy import types
from sqlalchemy.dialects.mysql.base import MSBinary
from sqlalchemy.schema import Column
import uuid
class UUID(types.TypeDecorator):
impl = MSBinary
def __init__(self):
self.impl.length = 16
types.TypeDecorator.__init__(sel...
INSERT with SELECT
... lets you put whatever you inserted into another table also. I don't think MySQL has an equivalent. You might create a temporary table, select into that table, then populate courses from that table, then use the temp table for whatever else you needed.
– Andrew
...
What does the KEY keyword mean?
In this MySQL table definition:
2 Answers
2
...
SQL UPDATE all values in a field with appended string CONCAT not working
...
That's pretty much all you need:
mysql> select * from t;
+------+-------+
| id | data |
+------+-------+
| 1 | max |
| 2 | linda |
| 3 | sam |
| 4 | henry |
+------+-------+
4 rows in set (0.02 sec)
mysql> update t set data=concat(d...
Laravel Schema onDelete set null
...cument what options there are, but I think you can assume it's the default mysql values (see ../ vendor / laravel / framework / src / Illuminate / Database / Schema / Grammars / Grammar.php)
– Dirk Jan
Mar 23 at 14:47
...
Cannot change column used in a foreign key constraint
... DELETE ) will wait till timeout or UNLOCK TABLES; is executed
http://dev.mysql.com/doc/refman/5.5/en/lock-tables.html
EDIT 2: OP asked for a more detailed explanation of the line "The type and definition of foreign key field and reference must be equal. This means your foreign key disallows chang...
B-Tree vs Hash Table
In MySQL, an index type is a b-tree, and access an element in a b-tree is in logarithmic amortized time O(log(n)) .
5 Answ...