大约有 47,000 项符合查询结果（耗时：0.0337秒） [XML]
Which SQL query is faster? Filter on Join criteria or Where clause?
...LEFT JOIN
TableXRef x
ON x.TableAID = a.ID
AND a.ID = 1
LEFT JOIN
TableB b
ON x.TableBID = b.ID
or this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAID = a.ID
LEFT JOIN
TableB b
ON b.id = x.TableBID
WHERE a.id = 1
The...
Extract first item of each sublist
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201
Using list comprehension:
>>> lst = [['a','b','c'], [1,2,3], ['x','y','z']]
>>&g...
How to output only captured groups with sed?
...e output as well as specifying what you do want.
string='This is a sample 123 text and some 987 numbers'
echo "$string" | sed -rn 's/[^[:digit:]]*([[:digit:]]+)[^[:digit:]]+([[:digit:]]+)[^[:digit:]]*/\1 \2/p'
This says:
don't default to printing each line (-n)
exclude zero or more non-digits
i...
How can I convert a DateTime to the number of seconds since 1970?
...t a C# DateTime variable to Unix time, ie, the number of seconds since Jan 1st, 1970. It looks like a DateTime is actually implemented as the number of 'ticks' since Jan 1st, 0001.
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Elastic Search: how to see the indexed data
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171
Probably the easiest way to explore your ElasticSearch cluster is to use elasticsearch-head.
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How to debug Lock wait timeout exceeded on MySQL?
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11 Answers
11
Active
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“CASE” statement within “WHERE” clause in SQL Server 2008
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13 Answers
13
Active
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How to check whether a pandas DataFrame is empty?
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edited Dec 15 '17 at 17:37
Dave Thomas
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