大约有 19,000 项符合查询结果（耗时：0.0196秒） [XML]
select * vs select column
...the top of my head is when you want only the value of an indexed column in MySQL (for example, just to check for row existence), and you're using MyISAM storage engine, it'll grab the data from the MYI file, which could be in memory, and not even go to disk!
– Mike Sherov
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No module named MySQLdb
I am using Python version 2.5.4 and install MySQL version 5.0 and Django. Django is working fine with Python, but not MySQL. I am using it in Windows Vista.
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【BLE技术内幕】BLE技术揭秘 - 创客硬件开发 - 清泛IT论坛，有思想、有深度
...个时间点把数据包发送出去，怎么保证数据的完整性，ACK如何接收，如何进行重传，以及如何对链路进行管理和控制等等。LL层只负责把数据发出去或者收回来，对数据进行怎样的解析则交给上面的GAP或者ATTHost Controller Interface，...
MySQL error code: 1175 during UPDATE in MySQL Workbench
I'm trying to update the column visited to give it the value 1. I use MySQL workbench, and I'm writing the statement in the SQL editor from inside the workbench. I'm writing the following command:
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MySQL 'create schema' and 'create database' - Is there any difference
... between the create schema command and the create database command for MySQL.
6 Answers
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Unresolved reference issue in PyCharm
... by simply telling pycharm that you want to add the src folder as a source root, and then adding the sources root to your python path.
This way, you don't have to hard code things into your interpreter's settings:
Add src as a source content root:
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MySQL: Insert record if not exists in table
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if you need to get warning message you can afterwards do mysql> show warnings\G
– fiorentinoing
Oct 20 '16 at 18:59
2
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String concatenation in Ruby
...;< but that is not the usual way
With string interpolation
source = "#{ROOT_DIR}/#{project}/App.config"
with +
source = "#{ROOT_DIR}/" + project + "/App.config"
The second method seems to be more efficient in term of memory/speed from what I've seen (not measured though). All three methods ...
How do I add more members to my ENUM-type column in MySQL?
The MySQL reference manual does not provide a clearcut example on how to do this.
7 Answers
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How to 'insert if not exists' in MySQL?
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use INSERT IGNORE INTO table
see http://bogdan.org.ua/2007/10/18/mysql-insert-if-not-exists-syntax.html
there's also INSERT … ON DUPLICATE KEY UPDATE syntax, you can find explanations on dev.mysql.com
Post from bogdan.org.ua according to Google's webcache:
18th October 2007
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