大约有 16,000 项符合查询结果（耗时：0.0286秒） [XML]
WHERE vs HAVING
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If your calculated expression does not contain any aggregates, putting it into the WHERE clause will most probably be more efficient.
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Trimming a huge (3.5 GB) csv file to read into R
... rows (leading Access and SQL to choke). It's county level data set broken into segments, sub-segments, and sub-sub-segments (for a total of ~200 factors) for 40 years. In short, it's huge, and it's not going to fit into memory if I try to simply read it.
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String variable interpolation Java [duplicate]
...should avoid String.format. Check performance comparison among Java string interpolation from redfin.
– MiaeKim
Oct 22 '19 at 22:18
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How to “pretty” format JSON output in Ruby on Rails
...g to do with this patch. Also, Time.parse returns the same result when you convert the string back to time for both formats. It'd only be a minor inconvenience when searching logs for time stamps, but if you're grepping anyway adding a few \s+ isn't really a big deal.
– con--
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“Cloning” row or column vectors
...is useful to "clone" a row or column vector to a matrix. By cloning I mean converting a row vector such as
9 Answers
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SQL MAX of multiple columns?
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Necro'ing this older post, but you could wrap each date into a COALESCE to handle NULL's. One of those WHEN statements would then look like: WHEN Date1 >= COALESCE(Date2,'') AND Date1 >= COALESCE(Date3,'') THEN Date3 (do the same for the other when's)
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How to check if a String contains only ASCII?
...I singleton.
Here ASCII includes all ASCII characters including the non-printable characters lower than 0x20 (space) such as tabs, line-feed / return but also BEL with code 0x07 and DEL with code 0x7F.
This code incorrectly uses characters rather than code points, even if code points are indicated...
Find in Files: Search all code in Team Foundation Server
...ilter used for C# files (text) was not giving the results we wanted, so we convert source files to .htm files. We can now add additional meta-data to the files such as:
Author (we define it as the person that last checked in the file)
Color coding (on our todo-list)
Number of changes indicating po...
What does the keyword Set actually do in VBA?
...t is used to assign a reference to an object. The C equivalent would be
int i;
int* ref_i;
i = 4; // Assigning a value (in VBA: i = 4)
ref_i = &i; //assigning a reference (in VBA: set ref_i = i)
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Parsing CSV files in C#, with header
...ributes like default values, replacements for NULL values and so forth), point the FileHelpers engine at a file, and bingo - you get back all the entries from that file. One simple operation - great performance!
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