大约有 42,000 项符合查询结果（耗时：0.0333秒） [XML]
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), ...
Disable ONLY_FULL_GROUP_BY
...ove ONLY_FULL_GROUP_BY from mysql console
mysql > SET GLOBAL sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));
you can read more here
Solution 2: Remove ONLY_FULL_GROUP_BY from phpmyadmin
Open phpmyadmin & select localhost
Click on menu Variables & scroll down for sq...
MySQL string replace
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Yes, MySQL has a REPLACE() function:
mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
-> 'WwWwWw.mysql.com'
http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_replace
Note that it's easier if you make that an alias when using SELECT
SEL...
How to get Top 5 records in SqLite?
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SELECT * FROM Table_Name LIMIT 5;
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Determine device (iPhone, iPod Touch) with iOS
..._t size;
sysctlbyname("hw.machine", NULL, &size, NULL, 0);
char *machine = malloc(size);
sysctlbyname("hw.machine", machine, &size, NULL, 0);
NSString *platform = [NSString stringWithCString:machine encoding:NSUTF8StringEncoding];
free(machine);
if ([platf...
Trigger change() event when setting 's value with val() function
... easiest and best way to trigger change event when setting the value of select element.
5 Answers
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Read data from SqlDataReader
...you use indexes like reader.GetString(0) will it use the first column you selected in your query or the firstt column on the table. I have a table with 3 columns in order: ID, Dir, Email. My command selects dir and email. Will reader.GetStrting(0) retrieve dir or ID? Are the indexes based off t...
jQuery autocomplete tagging plug-in like StackOverflow's input tags? [closed]
...otstrap-tagsinput/examples/
(demo?) http://jcesar.artelogico.com/jquery-tagselector/
(demo?) http://remysharp.com/wp-content/uploads/2007/12/tagging.php
(demo?) http://pietschsoft.com/post/2011/09/09/Tag-Editor-Field-using-jQuery-similar-to-StackOverflow.aspx
Related:
https://meta.stackexchange....
powershell - extract file name and extension
...tated, use the BaseName and Extension properties:
PS C:\> dir *.xlsx | select BaseName,Extension
BaseName Extension
-------- ---------
StackOverflow.com Test Config .xlsx
If you are given the file name as part of string...
SQL Server Management Studio, how to get execution time down to milliseconds
...able in your proc:
DECLARE @EndTime datetime
DECLARE @StartTime datetime
SELECT @StartTime=GETDATE()
-- Write Your Query
SELECT @EndTime=GETDATE()
--This will return execution time of your query
SELECT DATEDIFF(ms,@StartTime,@EndTime) AS [Duration in millisecs]
AND see this
Measuring Quer...