大约有 40,000 项符合查询结果（耗时：0.0509秒） [XML]
Clustered vs Non-Clustered
... PersonId means that the rows will be physically sorted by PersonId in the table, allowing an index search on this to go straight to the row (rather than a non-clustered index, which would direct you to the row's location, adding an extra step).
That said, it's unusual for the primary key not to be...
Random record in ActiveRecord
I'm in need of getting a random record from a table via ActiveRecord. I've followed the example from Jamis Buck from 2006 .
...
Using an RDBMS as event sourcing storage
...1 and 2 at all.
Below is the schema as used in Ncqrs. As you can see, the table "Events" stores the related data as a CLOB (i.e. JSON or XML). This corresponds to your option 3 (Only that there is no "ProductEvents" table because you only need one generic "Events" table. In Ncqrs the mapping to you...
Knight's Shortest Path on Chessboard
...tance(x,y)+'</td>';
}
html += '</tr>';
}
html = '<table>'+html+'</table>';
$body.append(html);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Note: The jQuery used for only illustration, for code see dis...
Rename column SQL Server 2008
I am using SQL Server 2008 and Navicat. I need to rename a column in a table using SQL.
11 Answers
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JOIN two SELECT statement results
....[# Late], 0) AS [# Late]
FROM
(SELECT ks, COUNT(*) AS '# Tasks' FROM Table GROUP BY ks) t1
LEFT JOIN
(SELECT ks, COUNT(*) AS '# Late' FROM Table WHERE Age > Palt GROUP BY ks) t2
ON (t1.ks = t2.ks);
share
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Can I add a UNIQUE constraint to a PostgreSQL table, after it's already created?
I have the following table:
4 Answers
4
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Changing the size of a column referenced by a schema-bound view in SQL Server
...SDN:
SCHEMABINDING
Binds the view to the schema of the underlying table or tables. When
SCHEMABINDING is specified, the base
table or tables cannot be modified in
a way that would affect the view
definition. The view definition itself
must first be modified or dropped to
remove ...
How to join (merge) data frames (inner, outer, left, right)
...f performance is a major issue for you, you should also look into the data.table package - that's a whole new set of join syntax, but it's radically faster than anything we're talking about here.
– Matt Parker
Feb 12 '13 at 16:22
...
MySQL Multiple Joins in one query?
...ally works? Is the second join joining the results of the first join with table 3, or is it joining table 1 with table 3 separately? (i.e., joining table 1 with table 2, and then joining table 1 separately with table 3, then returning it all back?) Does that make sense? I ask because I've been do...