大约有 44,000 项符合查询结果（耗时：0.0379秒） [XML]
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...
How to see full query from SHOW PROCESSLIST
... pull the data and look at 'INFO' column which contains the whole query :
select * from INFORMATION_SCHEMA.PROCESSLIST where db = 'somedb';
You can add any condition or ignore based on your requirement.
The output of the query is resulted as :
+-------+------+-----------------+--------+--------...
How many GCC optimization levels are there?
...?
integral_argument also thinly wraps atoi and rejects the argument if any character is not a digit. So negative values fail gracefully.
Back to opts.c:default_options_optimization, we see the line:
if ((unsigned int) opts->x_optimize > 255)
opts->x_optimize = 255;
so that the optimizati...
Rails: Using greater than/less than with a where statement
...s behavior.
User.where(id: 201..Float::INFINITY)
will generate the SQL
SELECT `users`.* FROM `users` WHERE (`users`.`id` >= 201)
The same can be done for less than with -Float::INFINITY.
I just posted a similar question asking about doing this with dates here on SO.
>= vs >
To avo...
In a storyboard, how do I make a custom cell for use with multiple controllers?
... = [controller.tableView indexPathForCell:self];
[controller.tableView selectRowAtIndexPath:path animated:NO scrollPosition:UITableViewScrollPositionNone];
[controller performSegueWithIdentifier:@"FinishedTask" sender:controller];
[super touchesEnded:touches withEvent:event];
}
@end
I...
Is there a __CLASS__ macro in C++?
...
That's better. As for knowing the class, defining char array sounds better than postponing it till runtime.
– Michael Krelin - hacker
Nov 3 '09 at 12:21
5
...
Accessing an SQLite Database in Swift
...pared statement: \(errmsg)")
}
statement = nil
Prepare new statement for selecting values from table and loop through retrieving the values:
if sqlite3_prepare_v2(db, "select id, name from test", -1, &statement, nil) != SQLITE_OK {
let errmsg = String(cString: sqlite3_errmsg(db)!)
pri...
LINQ To Entities does not recognize the method Last. Really?
...e fact that eventually it has to translate that query to SQL and SQL has a SELECT TOP (in T-SQL) but not a SELECT BOTTOM (no such thing).
There is an easy way around it though, just order descending and then do a First(), which is what you did.
EDIT:
Other providers will possibly have different im...
Explicit vs implicit SQL joins
...e joined and how they are joined. Try compare larger SQL queries where you selecting from 8 different tables and you have lots of filtering in the where. By using join syntax you separate out the parts where the tables are joined, to the part where you are filtering the rows.
...
Keeping it simple and how to do multiple CTE in a query
...s in one query, as well as reuse a CTE:
WITH cte1 AS
(
SELECT 1 AS id
),
cte2 AS
(
SELECT 2 AS id
)
SELECT *
FROM cte1
UNION ALL
SELECT *
FROM cte2
UNION ALL
SELECT *
FROM cte1
Note, however, that SQL Server may reevaluate t...