大约有 41,000 项符合查询结果（耗时：0.0330秒） [XML]
What does SQL clause “GROUP BY 1” mean?
...
SELECT account_id, open_emp_id
^^^^ ^^^^
1 2
FROM account
GROUP BY 1;
In above query GROUP BY 1 refers to the first column in select statement which is
account_id.
You also can speci...
PostgreSQL: Modify OWNER on all tables simultaneously in PostgreSQL
...and sequences too. Here's what I did:
Tables:
for tbl in `psql -qAt -c "select tablename from pg_tables where schemaname = 'public';" YOUR_DB` ; do psql -c "alter table \"$tbl\" owner to NEW_OWNER" YOUR_DB ; done
Sequences:
for tbl in `psql -qAt -c "select sequence_name from information_schem...
Database Diagram Support Objects cannot be Installed … no valid owner
...rator and this has also invalidated the current owner of the database.
If SELECT @@SERVERNAME; is not accurate (it should say DevPC), then in order to ensure that your server rename has taken hold within SQL Server, you may also want to issue the following:
EXEC sp_dropserver @server = N'old serve...
getting exception “IllegalStateException: Can not perform this action after onSaveInstanceState”
...
@t0mm13b: to add more as 600 chars are not enough, you have to investigate first what is really causing this for you. You have also to realize that above is an ugly hack and I am not taking any responsibility if it runs or not (for me was the best soluti...
Auto-expanding layout with Qt-Designer
...your widget/dialog/window (not the QVBoxLayout, but the parent widget) and select Lay Out -> Lay Out in a Grid from the bottom of the context-menu. The QVBoxLayout should now stretch to fit the window and will resize automatically when the entire window is resized.
...
Selecting last element in JavaScript array [duplicate]
...gth less 1.
Mozilla Docs on Slice
Performance of the various methods for selecting last array element
share
|
improve this answer
|
follow
|
...
COUNT DISTINCT with CONDITIONS
...
You can try this:
select
count(distinct tag) as tag_count,
count(distinct (case when entryId > 0 then tag end)) as positive_tag_count
from
your_table_name;
The first count(distinct...) is easy.
The second one, looks somewhat complex...
Copy/duplicate database without using mysqldump
...the references, you can run the following to copy the data:
INSERT INTO x SELECT * FROM other_db.y;
If you're using MyISAM, you're better off to copy the table files; it'll be much faster. You should be able to do the same if you're using INNODB with per table table spaces.
If you do end up doin...
How to use range-based for() loop with std::map?
...
If copy assignment operator of foo and bar is cheap (eg. int, char, pointer etc), you can do the following:
foo f; bar b;
BOOST_FOREACH(boost::tie(f,b),testing)
{
cout << "Foo is " << f << " Bar is " << b;
}
...
SQL how to make null values come last when sorting ascending
...
select MyDate
from MyTable
order by case when MyDate is null then 1 else 0 end, MyDate
share
|
improve this answer
...