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Does SQLAlchemy have an equivalent of Django's get_or_create?
...ote that begin_nested automatically triggers a flush.
Note that if using MySQL, the transaction isolation level must be set to READ COMMITTED rather than REPEATABLE READ for this to work. Django's get_or_create (and here) uses the same stratagem, see also the Django documentation.
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How do I find which transaction is causing a “Waiting for table metadata lock” state?
...ransactions waiting for locks:
SELECT TRX_ID, TRX_REQUESTED_LOCK_ID, TRX_MYSQL_THREAD_ID, TRX_QUERY
FROM INNODB_TRX
WHERE TRX_STATE = 'LOCK WAIT';
Reference - MySQL Troubleshooting: What To Do When Queries Don't Work, Chapter 6 - Page 96.
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ALTER TABLE without locking the table?
When doing an ALTER TABLE statement in MySQL, the whole table is read-locked (allowing concurrent reads, but prohibiting concurrent writes) for the duration of the statement. If it's a big table, INSERT or UPDATE statements could be blocked for a looooong time. Is there a way to do a "hot alter", li...
How do I use installed packages in PyCharm?
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For me, it was just a matter of marking the directory as a source root.
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mysql query order by multiple items
..._activity ASC so sort direction for each column, default sort direction in mysql (with default configuration) is ASC.
– ZurabWeb
Jan 30 '14 at 20:29
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How do I return rows with a specific value first?
...L Server, but that's because the syntax is non-standard and only works for MySQL. When using a CASE statement (which is standard SQL) SQL Server can very well use an expression in the ORDER BY clause. "too stupid to process equivalency tests" is simply wrong. If at all it should read: "does not supp...
MQTT与TCP的区别 - 创客硬件开发 - 清泛IT社区，为创新赋能！
... Maori dictionary)。10. mqtt客户端connect时，可以带有用户名和密码，用于验证客户端。服务端可以根据clientid、IP地址、用户名等进行ACL访问控制。可以通过自定义应用消息实现客户端对服务端的身份验证。11. 有商业和开源的mqtt broke...
MySql - Way to update portion of a string?
I'm looking for a way to update just a portion of a string via MySQL query.
4 Answers
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How to install the Raspberry Pi cross compiler on my Linux host machine?
...crosstool-ng/builds/arm-l
inux-gnueabihf-raspbian-linux/install --with-sysroot=/cbuild/slaves/oort61/crosstool-ng/builds/
arm-linux-gnueabihf-raspbian-linux/install/arm-linux-gnueabihf/libc --enable-languages=c,c++,fo
rtran --disable-multilib --with-arch=armv6 --with-tune=arm1176jz-s --with-fpu=v...
MySQL Select minimum/maximum among two (or more) given values
...1) AS date1
FROM A, B
WHERE B.x = A.x
Both are described here http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html
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