大约有 44,000 项符合查询结果（耗时：0.0849秒） [XML]
JOIN queries vs multiple queries
...t of things. Jeff Atwood (founder of this site) actually wrote about this. For the most part, though, if you have the right indexes and you properly do your JOINs it is usually going to be faster to do 1 trip than several.
s...
Drop all tables whose names begin with a certain string
... than one in the database.
DECLARE @cmd varchar(4000)
DECLARE cmds CURSOR FOR
SELECT 'drop table [' + Table_Name + ']'
FROM INFORMATION_SCHEMA.TABLES
WHERE Table_Name LIKE 'prefix%'
OPEN cmds
WHILE 1 = 1
BEGIN
FETCH cmds INTO @cmd
IF @@fetch_status != 0 BREAK
EXEC(@cmd)
END
CLOSE cmds;...
SQL WHERE condition is not equal to?
...
There you go, edited the answer to remove the * Thanks for pointing out.
– Praveen Lobo
May 27 '11 at 21:45
5
...
How to use NSJSONSerialization
...;e];
if (!jsonArray) {
NSLog(@"Error parsing JSON: %@", e);
} else {
for(NSDictionary *item in jsonArray) {
NSLog(@"Item: %@", item);
}
}
share
|
improve this answer
|
...
Union Vs Concat in Linq
...e comments. If you execute my sample code then you can see the same result for 'a5' & 'a6'. I am not looking for solution. But why 'Concat' & 'Union' behaving same at that sistuation. Please reply.
– Prasad Kanaparthi
Nov 16 '12 at 17:29
...
Select random row from a sqlite table
...ible to seed the random number. e.g. Book of the day seeded with unix epoc for today at noon so it shows the same book all day even if the query is run multiple times. Yes I know caching is more efficient for this use case just an example.
– danielson317
Apr 22...
Show dialog from fragment?
...
Unfortunately this approach is a bit more verbose than the classic managed dialogs approach of previous Android revisions, but it is now the preferred method. You can avoid referencing the Activity entirely by using the putFrag...
How to concatenate strings of a string field in a PostgreSQL 'group by' query?
I am looking for a way to concatenate the strings of a field within a group by query. So for example, I have a table:
14 An...
MySQL Cannot Add Foreign Key Constraint
So I'm trying to add Foreign Key constraints to my database as a project requirement and it worked the first time or two on different tables, but I have two tables on which I get an error when trying to add the Foreign Key Constraints.
The error message that I get is:
...
How to implement WiX installer upgrade?
At work we use WiX for building installation packages. We want that installation of product X would result in uninstall of the previous version of that product on that machine.
...