大约有 6,100 项符合查询结果（耗时：0.0237秒） [XML]
Facebook database design?
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Keep a friend table that holds the UserID and then the UserID of the friend (we will call it FriendID). Both columns would be foreign keys back to the Users table.
Somewhat useful example:
Table Name: User
Columns:
UserID PK
Emai...
Angular.js ng-repeat across multiple tr's
...test through an html validator allowed multiple tbody elements in the same table.
Update: As of at least Angular 1.2 there is an ng-repeat-start and ng-repeat-end to allow repeating a series of elements. See the documentation for more information and thanks to @Onite for the comment!
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How are Python's Built In Dictionaries Implemented?
...r python is implemented? My understanding is that it is some sort of hash table, but I haven't been able to find any sort of definitive answer.
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float:left; vs display:inline; vs display:inline-block; vs display:table-cell;
...(the best is simply to not have any spaces between the elements)
display:table-cell;
Another one where you'll have problems with browser compatibility. Older IEs won't work with this at all. But even for other browsers, it's worth noting that table-cell is designed to be used in a context of being...
Repeat each row of data.frame the number of times specified in a column
...ndRows(df, "freq")
Simple syntax, very fast, works on data.frame or data.table.
Result:
var1 var2
1 a d
2 b e
2.1 b e
3 c f
3.1 c f
3.2 c f
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How do I use ROW_NUMBER()?
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For the first question, why not just use?
SELECT COUNT(*) FROM myTable
to get the count.
And for the second question, the primary key of the row is what should be used to identify a particular row. Don't try and use the row number for that.
If you returned Row_Number() in your main...
Turning a Comma Separated string into individual rows
I have a SQL Table like this:
16 Answers
16
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Select first row in each GROUP BY group?
...also supports window functions (the CTE needs to be converted to a derived table though). And Firebird 3.0 will also support Window functions
– a_horse_with_no_name
Mar 14 '14 at 9:19
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OPTION (RECOMPILE) is Always Faster; Why?
...You hit the nail on the head when you mentioned a query initially run on a table with 10 records, and now the table has millions of records. That was my case exactly. I didn't mention it in the post because I didn't think it mattered. Fascinating stuff. Thanks again.
– Chad Dec...
Postgres: clear entire database before re-creating / re-populating from bash script
...g_dump and pg_restore directly together over a pipe.
To drop and recreate tables, you could use the --clean command-line option for pg_dump to emit SQL commands to clean (drop) database objects prior to (the commands for) creating them. (This will not drop the whole database, just each table/sequen...