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Favourite performance tuning tricks [closed]
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Assuming MySQL here, use EXPLAIN to find out what is going on with the query, make sure that the indexes are being used as efficiently as possible and try to eliminate file sorts. High Performance MySQL: Optimization, Backups, Replica...
How to change the name of a Django app?
...E <oldAppName>_modelName RENAME TO <newAppName>_modelName. For mysql too I think it is the same (as mentioned by @null_radix)
(For Django >= 1.7) Update the django_migrations table to avoid having your previous migrations re-run: UPDATE django_migrations SET app='<NewAppName>' W...
Auto increment in phpmyadmin
I have an existing database using PHP, MySQL and phpMyAdmin.
9 Answers
9
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How to get last inserted row ID from WordPress database?
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Putting the call to mysql_insert_id() inside a transaction, should do it:
mysql_query('BEGIN');
// Whatever code that does the insert here.
$id = mysql_insert_id();
mysql_query('COMMIT');
// Stuff with $id.
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Check if table exists without using “select from”
...elf stated to do it is the proper way. There is no 'exists' type statement MySql. 'Exists' in MySql is a clause which requires an operation such as SELECT, UPDATE, or DELETE.
– doogle
Jan 12 '12 at 1:51
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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
Referring to a Column Alias in a WHERE Clause
... I think using HAVING on aliases is not standard (it does works on MySQL, though). Specifically, I think it does not work with SQL Server.
– tokland
Nov 25 '16 at 12:10
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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 ...