大约有 6,000 项符合查询结果（耗时：0.0360秒） [XML]
Overriding a Rails default_scope
... like: def self.random; unscoped.order('rand()'); end unscoped removes ALL sql before it, not just what is listed under default_scope. While technically a correct answer, be careful using unstopped
– Schneems
Dec 25 '11 at 21:58
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Retrieving the last record in each group - MySQL
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MySQL 8.0 now supports windowing functions, like almost all popular SQL implementations. With this standard syntax, we can write greatest-n-per-group queries:
WITH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITIO...
In MySQL queries, why use join instead of where?
...d
From a Performance Perspective:
Where supported (Oracle 9i+, PostgreSQL 7.2+, MySQL 3.23+, SQL Server 2000+), there is no performance benefit to using either syntax over the other. The optimizer sees them as the same query. But more complex queries can benefit from using ANSI-92 syntax:
A...
Create a new database with MySQL Workbench
Being new to MySQL, I have installed the latest version of the MySQL Workbench (5.2.33). I would like to know how you can create a database with this application. In the Overview tab of the SQL editor there are few "MySQL Schema" displayed, are these schemas the existing databases?
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MySQL root password change
I have been trying to reset my MySQL root password. I have run the mysqld_safe --skip-grant-tables, updated the root password, and checked the user table to make sure it is there. Once restarting the mysql daemon I tried logging in with the new root password that I just set and still get Access de...
Altering a column: null to not null
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Its strange the MS SQL Management Studio does not allow that option, it brags about "Dropping table ..."
– Sebastian
May 2 '13 at 11:25
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Is there a query language for JSON?
Is there a (roughly) SQL or XQuery-like language for querying JSON?
22 Answers
22
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MySQL, update multiple tables with one query
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If I want to include "LIMIT" to the SQL Query, do I have to say LIMIT 1 or LIMIT 2?
– Bluedayz
Aug 25 '14 at 16:31
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How to dynamically compose an OR query filter in Django?
..._objects)
# sometimes the following is helpful for debugging (returns the SQL statement)
# print queryset.query
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What is the MySQL JDBC driver connection string?
I am new to JDBC and I am trying to make a connection to a MySQL database.
I am using Connector/J driver, but I cant find the JDBC connection string for my Class.forName() method.
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