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Possible to do a MySQL foreign key to one of two possible tables?
...ut logical XOR is not standard SQL and is not supported by all SQL brands. MySQL has it, but PostgreSQL does not. Oracle has it, but Microsoft does not until 2016. And so on.
– Bill Karwin
Aug 19 '15 at 15:09
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MySql Table Insert if not exist otherwise update
... re-written using the proper INSERT ... ON DUPLICATE KEY UPDATE syntax for MySQL:
INSERT INTO AggregatedData (datenum,Timestamp)
VALUES ("734152.979166667","2010-01-14 23:30:00.000")
ON DUPLICATE KEY UPDATE
Timestamp=VALUES(Timestamp)
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How to take backup of a single table in a MySQL database?
By default, mysqldump takes the backup of an entire database. I need to backup a single table in MySQL. Is it possible? How do I restore it?
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实战做项目如何选择开源许可协议（一）-了解协议 - 开源 & Github - 清泛网...
实战做项目如何选择开源许可协议（一）-了解协议opensource_permission目前国内开源项目正在逐渐升温，中国也开始有不少优秀的开源项目突显出来。在大家摩拳擦掌准备加入开源大军时，也要知道这个圈子里的规则。...目前国内...
Optimal way to concatenate/aggregate strings
...com/en-us/sql/t-sql/functions/string-agg-transact-sql
GROUP_CONCAT() in MySQL
http://dev.mysql.com/doc/refman/5.7/en/group-by-functions.html#function_group-concat
(Thanks to @Brianjorden and @milanio for Azure update)
Example Code:
select Id
, STRING_AGG(Name, ', ') Names
from Demo
group by I...
Create new user in MySQL and give it full access to one database
I want to create a new user in MySQL and give it full access only to one database, say dbTest , that I create with a command like create database dbTest; . What would be the MySQL commands to do that?
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Is there a REAL performance difference between INT and VARCHAR primary keys?
...e performance difference between using INT vs. VARCHAR as a primary key in MySQL? I'd like to use VARCHAR as the primary key for reference lists (think US States, Country Codes) and a coworker won't budge on the INT AUTO_INCREMENT as a primary key for all tables.
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Can't connect to local MySQL server through socket '/var/mysql/mysql.sock' (38)
I am having a big problem trying to connect to mysql. When I run:
41 Answers
41
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PDOException SQLSTATE[HY000] [2002] No such file or directory
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The error message indicates that a MySQL connection via socket is tried (which is not supported).
In the context of Laravel (artisan), you probably want to use a different / the correct environment. Eg: php artisan migrate --env=production (or whatever enviro...
App Inventor 2 低功耗蓝牙(BLE) 硬件接入、数据通信及IO控制 - App Invent...
...本文主要介绍一款较为通用、价格低廉的BLE设备从零开始如何利用App Inventor 2开发一款自己专属的手机蓝牙App应用。BLE与经典蓝牙的区别可参考：《低功耗蓝牙(BLE) 和 经典蓝牙(SPP) 的区别》。本文主要通过一款常见的BLE硬件接入...