大约有 45,000 项符合查询结果（耗时：0.0288秒） [XML]
PostgreSQL function for last inserted ID
...e:
INSERT INTO persons (lastname,firstname) VALUES ('Smith', 'John');
SELECT currval('persons_id_seq');
The name of the sequence must be known, it's really arbitrary; in this example we assume that the table persons has an id column created with the SERIAL pseudo-type. To avoid relying on thi...
postgresql: INSERT INTO … (SELECT * …)
...ostgres
CREATE TABLE tblA (id serial, time integer);
INSERT INTO tblA
SELECT id, time
FROM dblink('dbname=dbtest', 'SELECT id, time FROM tblB')
AS t(id integer, time integer)
WHERE time > 1000;
TABLE tblA;
id | time
----+------
1 | 5000
2 | 2000
(2 rows)
PostgreSQL has ...
T-SQL: Deleting all duplicate rows but keeping one [duplicate]
... I do not care about that. I still need to keep one of these rows however. SELECT DISTINCT won't work because it operates on all columns and I need to suppress duplicates based on the key columns.
...
getMinutes() 0-9 - How to display two digit numbers?
...rent_date.getMinutes()).slice(-2);
The technique is take the rightmost 2 characters (slice(-2)) of "0" prepended onto the string value of getMinutes(). So:
"0"+"12" -> "012".slice(-2) -> "12"
and
"0"+"1" -> "01".slice(-2) -> "01"
...
PostgreSQL - fetch the row which has the Max value for a column
...sted index lookup into lives - on my machine
-- the latter query plan was selected given my memory settings and
-- histogram
SELECT
l1.*
FROM
lives AS l1
INNER JOIN (
SELECT
usr_id,
MAX(time_stamp) AS time_stamp_max
FROM
lives
GROUP BY
usr_id
) AS l2
...
Postgres: INSERT if does not exist already
...onditional INSERT in PostgreSQL:
INSERT INTO example_table
(id, name)
SELECT 1, 'John'
WHERE
NOT EXISTS (
SELECT id FROM example_table WHERE id = 1
);
CAVEAT This approach is not 100% reliable for concurrent write operations, though. There is a very tiny race condition between...
What is the “assert” function?
... not raise an exception, it has parentheses around its argument, and the # character does not introduce a comment.
– Steve Jessop
Oct 15 '09 at 11:36
...
How to un-escape a backslash-escaped string?
...WARNING: value.encode('utf-8').decode('unicode_escape') corrupts non-ASCII characters in the string. Unless the input is guaranteed to only contain ASCII characters, this is not a valid solution.
– Alex Peters
Jun 9 '19 at 11:46
...
How to drive C#, C++ or Java compiler to compute 1+2+3+…+1000 at compile time?
...
C# example to error at compile time.
class Foo
{
const char Sum = (1000 + 1) * 1000 / 2;
}
Produces the following compilation error:
Constant value '500500' cannot be converted to a 'char'
share
...
Select distinct using linq [duplicate]
...
myList.GroupBy(test => test.id)
.Select(grp => grp.First());
Edit: as getting this IEnumerable<> into a List<> seems to be a mystery to many people, you can simply write:
var result = myList.GroupBy(test => test.id)
.S...