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How to get current date & time in MySQL?
...rent date in epoch format, then you can use UNIX_TIMESTAMP(). For example:
select now(3), sysdate(3), unix_timestamp();
would yield
+-------------------------+-------------------------+------------------+
| now(3) | sysdate(3) | unix_timestamp() |
+--------------------...
Why is a “GRANT USAGE” created the first time I grant a user privileges?
...henticate. An user with USAGE privilege can run certain SQL commands like 'select 1+1' and 'show processlist'.
– Mircea Vutcovici
Feb 26 '15 at 16:10
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Difference between string and text in rails?
... load varchar in one go, but store text (and blob) outside of the table. A SELECT name, amount FROM products could, be a lot slower when using text for name than when you use varchar. And since Rails, by default loads records with SELECT * FROM... your text-columns will be loaded. This will probably...
Join between tables in two different databases?
...
Yes, assuming the account has appropriate permissions you can use:
SELECT <...>
FROM A.table1 t1 JOIN B.table2 t2 ON t2.column2 = t1.column1;
You just need to prefix the table reference with the name of the database it resides in.
...
How to send an email with Python?
...se user:
If you use 126/163, 网易邮箱, you need to set"客户端授权密码", like below:
ref: https://stackoverflow.com/a/41470149/2803344
https://docs.python.org/3/library/email.examples.html#email-examples
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...
What is a proper naming convention for MySQL FKs?
... foreign key constraint name by running a query:
use information_schema;
select TABLE_NAME,COLUMN_NAME,CONSTRAINT_NAME, REFERENCED_TABLE_NAME,REFERENCED_COLUMN_NAME from KEY_COLUMN_USAGE where REFERENCED_TABLE_SCHEMA = 'your_db_schema_name' ORDER BY TABLE_NAME;
For example you might receive the ...
How to change the foreign key referential action? (behavior)
...r, so I wrote something to make the statements for me. Figured I'd share:
SELECT
CONCAT('ALTER TABLE `' ,rc.TABLE_NAME,
'` DROP FOREIGN KEY `' ,rc.CONSTRAINT_NAME,'`;')
, CONCAT('ALTER TABLE `' ,rc.TABLE_NAME,
'` ADD CONSTRAINT `' ,rc.CONSTRAINT_NAME ,'` FOREIGN KEY (`',kcu.COLUMN_NAME,
...
2015年硅谷最火的高科技创业公司都有哪些 - 资讯 - 清泛网 - 专注C/C++及内核技术
...算机届最高奖以他命名)艰难的一生，他当年为破译德军密码制作了图灵机为二战胜利作出卓越贡献，挽回几千万人的生命，可在那个时代因为同性恋被判化学阉割，自杀结束了短暂的42岁生命。他的一个伟大贡献就是在人工智能...
ORDER BY the IN value list
... (introduced in PostgreSQL 8.2) VALUES (), ().
Syntax will be like this:
select c.*
from comments c
join (
values
(1,1),
(3,2),
(2,3),
(4,4)
) as x (id, ordering) on c.id = x.id
order by x.ordering
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How to use index in select statement?
...
If you want to test the index to see if it works, here is the syntax:
SELECT *
FROM Table WITH(INDEX(Index_Name))
The WITH statement will force the index to be used.
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