大约有 48,000 项符合查询结果（耗时：0.0174秒） [XML]
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...e.*)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
But don't use COUNT(*) for LEFT joins, as that will return 1 even if the subordinate table doesn't match anything from parent table
SELECT boss.boss_id, COUNT(*)
FROM boss
LEFT JOIN subordinate on subordin...
For each row return the column name of the largest value
...e to long putting all the departments in one column and counts in another, group by the employer id (in this case, the row number), and then filter to the department(s) with the max value. There are a couple of options for handling ties with this approach too.
library(tidyverse)
# sample data fram...
IIS_IUSRS and IUSR permissions in IIS8
...d as an object type for the name search (top field in the "Select Users or Groups" dialog).
– Jpsy
Jun 28 '18 at 8:31
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JUnit vs TestNG [closed]
... well.
TestNG has a neat feature where you can mark tests as a particular group, and then easily run all tests of a specific group, or exclude tests of a particular group. Thus you can mark tests that run slowly as in the "slow" group and then ignore them when you want quick results. A suggestion...
PostgreSQL: How to make “case-insensitive” query
... the strings to lower case before comparing.
Try this:
SELECT id
FROM groups
WHERE LOWER(name)=LOWER('Administrator')
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Regular Expression For Duplicate Words
...re \b is a word boundary and \1 references the captured match of the first group.
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Finding ALL duplicate rows, including “elements with smaller subscripts”
...ing
df = bind_rows(iris, head(iris, 20)) # build some test data
df %>% group_by_all() %>% filter(n()>1) %>% ungroup()
To exclude certain columns group_by_at(vars(-var1, -var2)) could be used instead to group the data.
If the row indices and not just the data is actually needed, you c...
GroupBy pandas DataFrame and select most common value
... valid for every combination of the first two. To clean the data I have to group by data frame by first two columns and select most common value of the third column for each combination.
...
PHP mkdir: Permission denied problem
...Here's what you do in Ubuntu
Make sure all files are owned by the Apache group and user. In Ubuntu it is the www-data group and user
chown -R www-data:www-data /path/to/webserver/www
Next enabled all members of the www-data group to read and write files
chmod -R g+rw /path/to/webserver/www
The...
Why can't radio buttons be “readonly”?
...you can just do onclick="return false;" to keep the value the same for the group
– Zach
Mar 7 '18 at 0:10
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