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Join between tables in two different databases?
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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.
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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,
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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
share
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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
share...
How to use index in select statement?
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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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...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...
jQuery OR Selector?
I am wondering if there is a way to have "OR" logic in jQuery selectors. For example, I know an element is either a descendant of an element with class classA or classB, and I want to do something like elem.parents('.classA or .classB') . Does jQuery provide such functionality?
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Increment a database field by 1
...complex depending on your specific needs:
INSERT into mytable (logins)
SELECT max(logins) + 1
FROM mytable
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How do I get IntelliJ IDEA to display directories?
...correctly. Make sure the "Content Root" is correct.
Click on the project
Select "File"->"Project Structure"
Select "modules" from the left column, and select a module.
On the sources tab you will see the current "Content Root" along with a button to add a new content root.
Make sure that con...