大约有 9,000 项符合查询结果（耗时：0.0284秒） [XML]
PostgreSQL query to return results as a comma separated list
...
SELECT string_agg(id::text, ',') FROM table
Requires PostgreSQL 9.0 but that's not a problem.
share
|
improve this answer
|
follow
|
...
How can I delete a file from a Git repository?
....
git filter-branch -f --index-filter 'git rm --cached --ignore-unmatch *.sql'
Note: Replace *.sql with your file name or file type. Be very careful because this will go through every commit and rip this file type out.
EDIT:
pay attention - after this command you will not be able to push or pul...
What is the difference between an ORM and an ODM?
...bject Document Mapper) deals with documents. Am I right in assuming that mySQL is an example of ORM and MongoDB is a example of ODM?
...
Set value to NULL in MySQL
...
You're probably quoting 'NULL'. NULL is a reserved word in MySQL, and can be inserted/updated without quotes:
INSERT INTO user (name, something_optional) VALUES ("Joe", NULL);
UPDATE user SET something_optional = NULL;
...
MySQL - why not index every field?
...
The link is for MS SQL Server; this question is for MySQL
– OMG Ponies
Mar 26 '11 at 23:38
6
...
How to join (merge) data frames (inner, outer, left, right)
...
@MattParker I have been using sqldf package for a whole host of complex queries against dataframes, really needed it to do a self-cross join (ie data.frame cross-joining itself) I wonder how it compares from a performance perspective....???
...
Fixing slow initial load for IIS
... My problem was that my app was using Windows Integrated Authentication to SQL Server and the service profile was in a different domain than the server. This caused a cross-domain authentication from IIS to SQL upon app initialization - and this was the real source of my delay. I changed to using a ...
Entity Framework code first unique column
... your model field is a string, make sure it is not set to nvarchar(MAX) in SQL Server or you will see this error with Entity Framework Code First:
Column 'x' in table 'dbo.y' is of a type that is invalid for use as a key column in an index.
The reason is because of this:
SQL Server retains...
How do I escape a reserved word in Oracle?
In TSQL I could use something like Select [table] from tablename to select a column named "table".
5 Answers
...
Delete all Duplicate Rows except for One in MySQL? [duplicate]
How would I delete all duplicate data from a MySQL Table?
2 Answers
2
...