大约有 41,000 项符合查询结果（耗时：0.0298秒） [XML]
How to get a substring of text?
I have text with length ~700. How do I get only ~30 of its first characters?
5 Answers
...
How to create json by JavaScript for loop?
I have array of select tag.
5 Answers
5
...
Create PostgreSQL ROLE (user) if it doesn't exist
...r fashion to what you had in mind:
DO
$do$
BEGIN
IF NOT EXISTS (
SELECT FROM pg_catalog.pg_roles -- SELECT list can be empty for this
WHERE rolname = 'my_user') THEN
CREATE ROLE my_user LOGIN PASSWORD 'my_password';
END IF;
END
$do$;
(Building on @a_horse_with_no_name's...
Is it possible to insert multiple rows at a time in an SQLite database?
...
This can be recast into SQLite as:
INSERT INTO 'tablename'
SELECT 'data1' AS 'column1', 'data2' AS 'column2'
UNION ALL SELECT 'data1', 'data2'
UNION ALL SELECT 'data1', 'data2'
UNION ALL SELECT 'data1', 'data2'
a note on performance
I originally used this technique to efficiently lo...
Select every Nth element in CSS
Is it possible to select, say, every fourth element in a set of elements?
4 Answers
4
...
What are the lesser known but useful data structures?
...s are painfully expensive, given that a pointer is generally longer than a char, which is a shame. They're only suitable for certain data-sets.
– Joe
Jan 29 '10 at 12:06
18
...
How to get Last record from Sqlite?
...
Try this:
SELECT *
FROM TABLE
WHERE ID = (SELECT MAX(ID) FROM TABLE);
OR
you can also used following solution:
SELECT * FROM tablename ORDER BY column DESC LIMIT 1;
...
ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired
...table is already locked by some query. For example, you may have executed "select for update" and have not yet committed/rollbacked and fired another select query. Do a commit/rollback before executing your query.
share
...
Eclipse: How do i refresh an entire workspace? F5 doesn't do it
...le->Refresh , it doesn't really refresh anything (perhaps the currently selected project). How do I get eclipse to refresh all of the projects?
...
How to generate a random int in C?
...
If you need secure random characters or integers:
As addressed in how to safely generate random numbers in various programming languages, you'll want to do one of the following:
Use libsodium's randombytes API
Re-implement what you need from libsod...