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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...
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
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What does the KEY keyword mean?
In this MySQL table definition:
2 Answers
2
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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...
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
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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
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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...
C/C++中的段错误（Segmentation fault） - C/C++ - 清泛网 - 专注C/C++及内核技术
...麻烦”？
3。编程中通常碰到段错误的地方有哪些？
4。如何发现程序中的段错误并处理掉？
正文
1。什么是段错误？
下面是来自Answers.com的定义：
A segmentation fault (often shortened to segfault) is a particular error conditio...
How to change the CHARACTER SET (and COLLATION) throughout a database?
Our previous programmer set the wrong collation in a table (Mysql). He set it up with Latin collation, when it should be UTF8, and now I have issues. Every record with Chinese and Japan character turn to ??? character.
...