大约有 47,000 项符合查询结果（耗时：0.0376秒） [XML]
SQL left join vs multiple tables on FROM line?
...nts that have employees, but always list all companies.
So you do this:
SELECT * -- for simplicity
FROM Company, Department, Employee
WHERE Company.ID *= Department.CompanyID
AND Department.ID = Employee.DepartmentID
Note that the last one there is an inner join, in order to fulfill the crite...
Hidden Features of Xcode
...m working with a large or unfamiliar project.
To show the Favorites Bar, select the following menu option:
View > Layout > Show Favorites Bar
share
edited Apr 4 '11...
SQL order string as number
...u can't do that then cast your column value to an integer explicitly with
select col from yourtable
order by cast(col as unsigned)
or implicitly for instance with a mathematical operation which forces a conversion to number
select col from yourtable
order by col + 0
BTW MySQL converts strings...
Postgres could not connect to server
...
Had a similar problem; a pid file was blocking postgres from starting up. To fix it:
$ rm /usr/local/var/postgres/postmaster.pid
$ brew services restart postgresql
and then all is well.
share
|
...
Ruby: Easiest Way to Filter Hash Keys?
...answer: Even though this is answer (as of the time of this comment) is the selected answer, the original version of this answer is outdated.
I'm adding an update here to help others avoid getting sidetracked by this answer like I did.
As the other answer mentions, Ruby >= 2.5 added the Hash#sli...
What is the Windows version of cron? [closed]
...asks (Control Panel -> Scheduled Tasks), though they are a far, far cry from cron.
The biggest difference (to me) is that they require a user to be logged into the Windows box, and a user account (with password and all), which makes things a nightmare if your local security policy requires passw...
UPDATE multiple tables in MySQL using LEFT JOIN
...= t1.id
SET t1.col1 = newvalue
WHERE t2.id IS NULL
Note that for a SELECT it would be more efficient to use NOT IN / NOT EXISTS syntax:
SELECT t1.*
FROM t1
WHERE t1.id NOT IN
(
SELECT id
FROM t2
)
See the article in my blog for performance details...
Replace Default Null Values Returned From Left Outer Join
... for left outer join. Is there a way to replace the default values in the select statement? I have a workaround in that I can select into a table variable but it feels a little dirty.
...
How to integrate CSS pre-processing within Eclipse? [closed]
...and then click OK.
Find the *.scss entry in the File Associations list and select it.
After selecting *.scss, on the bottom pane Associated editors:, click the Add... button.
Make sure Internal editors is selected on the top, then find and select CSS Editor and then click OK.
This associated the f...
IntelliJ: Working on multiple projects
...ven Projects" window (View > Tool Windows > Maven Projects) and then select the additional pom file you want to import.
share
|
improve this answer
|
follow
...