大约有 44,000 项符合查询结果（耗时：0.0247秒） [XML]
How to implement a unique index on two columns in rails
I have a table and I'm trying to add a unique index on two columns. Those columns are also indexed. So my question is if I just can remove the indexes who were just for one column or if I have to use all three indexes:
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Change the name of the :id parameter in Routing resources for Rails
I looked around on how to change the dynamic params slot and found this post that does the exact thing.
The post is https://thoughtbot.com/blog/rails-patch-change-the-name-of-the-id-parameter-in
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What's the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN and FULL JOIN? [duplicate]
What's the difference between INNER JOIN , LEFT JOIN , RIGHT JOIN and FULL JOIN
in MySQL ?
3 Answers
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How to load external webpage inside WebView
...anks to this post, I finally found the solution. Here is the code:
import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebResourceError;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Toast...
MongoDB and “joins” [duplicate]
...ll only be evaluated when needed. A join (in a SQL database) on the other hand will resolve relationships and return them as if they were a single table (you "join two tables into one").
You can read more about DBRef here:
http://docs.mongodb.org/manual/applications/database-references/
There are ...
mongo group query how to keep fields
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@Juliomac, I believe if your desired output is $max/$min and keeping fields that are not in the $group _id, you can $sort before with the desired field then group and use $first or $last operators on any field. When accumulating, the idea to include other fields (which are accumula...
Remove an item from array using UnderscoreJS
...n-place, you have to use .splice. This is also shown in the other question and undescore doesn't seem to provide any useful function for that.
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SQLAlchemy: cascade delete
...ession.query().filter().delete() (which doesn't put elements in the memory and deletes directly from db).
Using this method sqlalchemy's cascade='all, delete' doesn't work. There is a solution though: ON DELETE CASCADE through db (note: not all databases support it).
class Child(Base):
__table...
Count with IF condition in MySQL query
I have two tables, one is for news and the other one is for comments and I want to get the count of the comments whose status has been set as approved.
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Python/postgres/psycopg2: getting ID of row just inserted
I'm using Python and psycopg2 to interface to postgres.
3 Answers
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