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How to check if a database exists in SQL Server?
...script:
DECLARE @dbname nvarchar(128)
SET @dbname = N'Senna'
IF (EXISTS (SELECT name
FROM master.dbo.sysdatabases
WHERE ('[' + name + ']' = @dbname
OR name = @dbname)))
-- code mine :)
PRINT 'db exists'
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Is there any performance gain in indexing a boolean field?
...
It depends on the actual queries and the selectivity of the index/query combination.
Case A: condition WHERE isok = 1 and nothing else there:
SELECT *
FROM tableX
WHERE isok = 1
If the index is selective enough (say you have 1M rows and only 1k have isok = 1), ...
jQuery - select the associated label element of a input field [duplicate]
I have a set of input fields, some of them have labels associated, some not:
3 Answers
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How to select an element with 2 classes [duplicate]
...
You can chain class selectors without a space between them:
.a.b {
color: #666;
}
Note that, if it matters to you, IE6 treats .a.b as .b, so in that browser both div.a.b and div.b will have gray text. See this answer for a comparison bet...
SQL Server : GROUP BY clause to get comma-separated values [duplicate]
...
try this:
SELECT ReportId, Email =
STUFF((SELECT ', ' + Email
FROM your_table b
WHERE b.ReportId = a.ReportId
FOR XML PATH('')), 1, 2, '')
FROM your_table a
GROUP BY ReportId
SQL fiddle demo
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Concatenate multiple result rows of one column into one, group by another column [duplicate]
...Simpler with the aggregate function string_agg() (Postgres 9.0 or later):
SELECT movie, string_agg(actor, ', ') AS actor_list
FROM tbl
GROUP BY 1;
The 1 in GROUP BY 1 is a positional reference and a shortcut for GROUP BY movie in this case.
string_agg() expects data type text as input. Other ...
SQL: How to perform string does not equal
...
Try the following query
select * from table
where NOT (tester = 'username')
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错误解决:Xcode not set up properly. You may need to confirm the licens...
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或
1
sudo -i xcode-select -switch /Applications/Xcode6-Beta6.app/Contents/Developer
根据具体路径：
（sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer）
升级xcode 后 Qt 出问题了，goo...
Cannot install Lxml on Mac os x 10.9
... or upgrade the commandline tool for xcode.
Try this in a terminal:
xcode-select --install
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What's is the difference between train, validation and test set, in neural networks?
...he validation data actually affects the weight configuration indirectly to select the weight configuration. This is where the Test set comes in. This set of data is never used in the training process. Once a model is selected based on the validation set, the test set data is applied on the network m...