大约有 41,000 项符合查询结果（耗时：0.0298秒） [XML]
INSERT INTO … SELECT FROM … ON DUPLICATE KEY UPDATE
...olumns named in the INSERT INTO clause, and the second part references the SELECT columns.
INSERT INTO lee(exp_id, created_by, location, animal, starttime, endtime, entct,
inact, inadur, inadist,
smlct, smldur, smldist,
larct, lardur, lardist,
...
SQLite select where empty?
In SQLite, how can I select records where some_column is empty?
Empty counts as both NULL and "".
4 Answers
...
Selecting only numeric columns from a data frame
...traightforward, and robust to use on database-back-ended tibbles:
dplyr::select_if(x, is.numeric)
share
|
improve this answer
|
follow
|
...
How to “git show” a merge commit with combined diff output even when every changed file agrees with
...ng this on the git repository on a8e4a59 shows a combined diff (plus/minus chars in one of 2 columns). As the git-show manual mentions, it pretty much delegates to 'git diff-tree' so those options look useful.
share
...
MySQL Select minimum/maximum among two (or more) given values
Is it possible to SELECT the minimum or maximum among two or more values. I'd need something like this:
4 Answers
...
How to trick an application into thinking its stdout is a terminal, not a pipe
...lt;&- script -qfc "git status" /dev/null | less -R . Those first few characters close stdin for this one commmand.
– Aaron McDaid
Nov 26 '14 at 13:54
...
What is your favorite C programming trick? [closed]
.... you could make a string "object" like this:
struct X {
int len;
char str[1];
};
int n = strlen("hello world");
struct X *string = malloc(sizeof(struct X) + n);
strcpy(string->str, "hello world");
string->len = n;
here, we've allocated a structure of type X on the heap that is the...
How to count occurrences of a column value efficiently in SQL?
...
This should work:
SELECT age, count(age)
FROM Students
GROUP by age
If you need the id as well you could include the above as a sub query like so:
SELECT S.id, S.age, C.cnt
FROM Students S
INNER JOIN (SELECT age, count(age) a...
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...k around it from within psql by executing the DDL statement conditionally:
SELECT 'CREATE DATABASE mydb'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'mydb')\gexec
The manual:
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's outpu...
Counting the number of option tags in a select tag in jQuery
How do I count the number of <option> s in a <select> DOM element using jQuery?
8 Answers
...