大约有 47,000 项符合查询结果（耗时：0.0378秒） [XML]
SQL Server 2008: How to query all databases sizes?
...
with fs
as
(
select database_id, type, size * 8.0 / 1024 size
from sys.master_files
)
select
name,
(select sum(size) from fs where type = 0 and fs.database_id = db.database_id) DataFileSizeMB,
(select sum(size) from fs wh...
How do SQL EXISTS statements work?
... criteria -- this is why it can be faster than IN. Also be aware that the SELECT clause in an EXISTS is ignored - IE:
SELECT s.*
FROM SUPPLIERS s
WHERE EXISTS (SELECT 1/0
FROM ORDERS o
WHERE o.supplier_id = s.supplier_id)
...should hit a division by zero error...
How to request a random row in SQL?
...
See this post: SQL to Select a random row from a database table. It goes through methods for doing this in MySQL, PostgreSQL, Microsoft SQL Server, IBM DB2 and Oracle (the following is copied from that link):
Select a random row with MySQL:
SELE...
Working with select using AngularJS's ng-options
...o work... note the ng-model="blah" which is saying "set $scope.blah to the selected value".
Try this:
<select ng-model="blah" ng-options="item.ID as item.Title for item in items"></select>
Here's more from AngularJS's documentation (if you haven't seen it):
for array data sources...
How to disable text selection highlighting
...S standard way to disable the highlighting effect if the user accidentally selects the text?
48 Answers
...
Select row with most recent date per user
...
Query:
SQLFIDDLEExample
SELECT t1.*
FROM lms_attendance t1
WHERE t1.time = (SELECT MAX(t2.time)
FROM lms_attendance t2
WHERE t2.user = t1.user)
Result:
| ID | USER | TIME | IO |
---------------------------...
How to add extra info to copied web text
...cument.location.href}`;
event.clipboardData.setData('text', document.getSelection() + pagelink);
event.preventDefault();
});
Lorem ipsum dolor sit amet, consectetur adipiscing elit.<br/>
<textarea name="textarea" rows="7" cols="50" placeholder="paste your copied text here"></...
Oracle SQL: Update a table with data from another table
...his is called a correlated update
UPDATE table1 t1
SET (name, desc) = (SELECT t2.name, t2.desc
FROM table2 t2
WHERE t1.id = t2.id)
WHERE EXISTS (
SELECT 1
FROM table2 t2
WHERE t1.id = t2.id )
Assuming the join results in a key-pr...
Get top n records for each group of grouped results
...ould need to specify the group number and add queries for each group:
(
select *
from mytable
where `group` = 1
order by age desc
LIMIT 2
)
UNION ALL
(
select *
from mytable
where `group` = 2
order by age desc
LIMIT 2
)
There are a variety of ways to do this, see this articl...
Difference between left join and right join in SQL Server [duplicate]
...
Select * from Table1 left join Table2 ...
and
Select * from Table2 right join Table1 ...
are indeed completely interchangeable. Try however Table2 left join Table1 (or its identical pair, Table1 right join Table2) to see...