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Explicit vs implicit SQL joins
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On MySQL 5.1.51, both queries have identical execution plans:
mysql> explain select * from table1 a inner join table2 b on a.pid = b.pid;
+----+-------------+-------+------+---------------+------+---------+--------------+---...
Convert a date format in PHP
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What if I get this date 0000-00-00 from mySQL? it returns a wrong date like 31/12/1969 ...
– Enrique
Apr 29 '10 at 22:20
3
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ALTER TABLE to add a composite primary key
...r table you will get an error when trying to drop it. In some versions of mysql the error message there was malformed (as of 5.5.17, this error message is still
alter table parent drop column id;
ERROR 1025 (HY000): Error on rename of
'./test/#sql-a04_b' to './test/parent' (errno: 150).
If you ...
What is the difference between Amazon S3 and Amazon EC2 instance?
I need to create a web application using php mysql and html. The no.of requests and data will be very high. I need Amazon server space.
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剖析程序的内存布局 - C/C++ - 清泛网 - 专注C/C++及内核技术
...拟地址空间的布局就讲这些吧。下一篇文章将讨论内核是如何跟踪这些内存区域的。我们会分析内存映射，看看文件的读写操作是如何与之关联的，以及内存使用概况的含义。
布局 内存 程序
What data type to use for hashed password field and what length?
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You can actually use CHAR(length of hash) to define your datatype for MySQL because each hashing algorithm will always evaluate out to the same number of characters. For example, SHA1 always returns a 40-character hexadecimal number.
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Checking if a field contains a string
.../reference/sql-comparison/
http://php.net/manual/en/mongo.sqltomongo.php
MySQL
SELECT * FROM users WHERE username LIKE "%Son%"
MongoDB
db.users.find({username:/Son/})
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how to get last insert id after insert query in codeigniter active record
...n insert query (active record style) used to insert the form fields into a MySQL table. I want to get the last auto-incremented id for the insert operation as the return value of my query but I have some problems with it.
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Why historically do people use 255 not 256 for database field magnitudes?
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255 was the varchar limit in mySQL4 and earlier.
Also 255 chars + Null terminator = 256
Or 1 byte length descriptor gives a possible range 0-255 chars
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京东618：算法让UV价值提升200%+，用智能卖场缩短购物路径 - 更多技术 - 清...
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CSDN：如果模型预测的结果为无货商品或下架商品，你们如何处理？
智能卖场团队：在推荐的结果中，如果出现无货或者下架的商品，我们将不会展示给用户。作为替代，我们将会给用户推荐它的相关或者相似的商品。这些相...