大约有 43,000 项符合查询结果（耗时：0.0319秒） [XML]
Select rows of a matrix that meet a condition
...20, ncol = 4)
colnames(m) <- letters[1:4]
The following command will select the first row of the matrix above.
subset(m, m[,4] == 16)
And this will select the last three.
subset(m, m[,4] > 17)
The result will be a matrix in both cases.
If you want to use column names to select columns...
How can I suppress column header output for a single SQL statement?
...in batch (using the mysql command-line binary). I want one of my several SELECT statements to not print the column headers, just the selected records. Is this possible?
...
How to generate a simple popup using jQuery
...
First the CSS - tweak this however you like:
a.selected {
background-color:#1F75CC;
color:white;
z-index:100;
}
.messagepop {
background-color:#FFFFFF;
border:1px solid #999999;
cursor:default;
display:none;
margin-top: 15px;
position:absolute;
text-a...
How to install Xcode Command Line Tools
...
Xcode 5.1 and OSX 10.9. (also works with Xcode 5.1.1 + OSX 10.10)
xcode-select --install worked with version 2333, failed with version 2003. So, try xcode-select --install and if that does not work download as described below.
In early February 2014 xcode-select --install has been reporting that...
Group by month and year in MySQL
...
I prefer
SELECT
MONTHNAME(t.summaryDateTime) as month, YEAR(t.summaryDateTime) as year
FROM
trading_summary t
GROUP BY EXTRACT(YEAR_MONTH FROM t.summaryDateTime) DESC";
...
What is SELF JOIN and when would you use it? [duplicate]
...et information for both people in one row, you could self join like this:
select e1.EmployeeID,
e1.FirstName,
e1.LastName,
e1.SupervisorID,
e2.FirstName as SupervisorFirstName,
e2.LastName as SupervisorLastName
from Employee e1
left outer join Employee e2 on e1.SupervisorID ...
How do I do multiple CASE WHEN conditions using SQL Server 2008?
...
Just use this one, You have to use more when they are classes.
SELECT Url='',
p.ArtNo,
p.[Description],
p.Specification,
CASE
WHEN 1 = 1 or 1 = 1
THEN 1
WHEN 2 = 2
THEN 2
WHEN 3 = 3
...
How do I get SUM function in MySQL to return '0' if no values are found?
...
Use COALESCE to avoid that outcome.
SELECT COALESCE(SUM(column),0)
FROM table
WHERE ...
To see it in action, please see this sql fiddle: http://www.sqlfiddle.com/#!2/d1542/3/0
More Information:
Given three tables (one with all numbers, one with all nul...
How do I copy to the clipboard in JavaScript?
...
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
console.log('Fallback: Copying text command was ' + msg);
} catch (err) {
consol...
How do you debug MySQL stored procedures?
...E debug_msg(enabled INTEGER, msg VARCHAR(255))
BEGIN
IF enabled THEN
select concat('** ', msg) AS '** DEBUG:';
END IF;
END $$
CREATE PROCEDURE test_procedure(arg1 INTEGER, arg2 INTEGER)
BEGIN
SET @enabled = TRUE;
call debug_msg(@enabled, 'my first debug message');
call debug_msg(@ena...