大约有 42,000 项符合查询结果（耗时：0.0394秒） [XML]
MySQL, better to insert NULL or empty string?
...insert a NULL value or an empty string into the DB columns where the user didn't put any data?
6 Answers
...
How can I remove or replace SVG content?
... the solution:
d3.select("svg").remove();
This is a remove function provided by D3.js.
share
|
improve this answer
|
follow
|
...
How to create a unique index on a NULL column?
...
It seems the content of the link you provided was actually (partially) copied without attribution from here: decipherinfosys.wordpress.com/2007/11/30/…
– Tom Juergens
Feb 25 '10 at 9:58
...
How do you obtain a Drawable object from a resource id in android package?
...o use the code below (or something like it) to get an object from the android.R.drawable.* package?
6 Answers
...
Insert, on duplicate update in PostgreSQL?
...ause. with the following syntax (similar to MySQL)
INSERT INTO the_table (id, column_1, column_2)
VALUES (1, 'A', 'X'), (2, 'B', 'Y'), (3, 'C', 'Z')
ON CONFLICT (id) DO UPDATE
SET column_1 = excluded.column_1,
column_2 = excluded.column_2;
Searching postgresql's email group archives ...
Hibernate, @SequenceGenerator and allocationSize
...y 50 (default allocationSize value) - and then uses this value as entity ID.
6 Answers
...
Hibernate throws org.hibernate.AnnotationException: No identifier specified for entity: com..domain.
...
You are missing a field annotated with @Id. Each @Entity needs an @Id - this is the primary key in the database.
If you don't want your entity to be persisted in a separate table, but rather be a part of other entities, you can use @Embeddable instead of @Entity....
Ways to save Backbone.js model data?
...erb you use. For example:
// The URI pattern
http://localhost:8888/donut/:id
// My URI call
http://localhost:8888/donut/17
If I make a GET to that URI, it would get donut model with an ID of 17. The :id depends on how you are saving it server side. This could just be the ID of your donut resourc...
How do I find a default constraint using INFORMATION_SCHEMA?
...l_columns
INNER JOIN
sys.tables
ON all_columns.object_id = tables.object_id
INNER JOIN
sys.schemas
ON tables.schema_id = schemas.schema_id
INNER JOIN
sys.default_constraints
ON all_columns.default_object_id = default_constraints.object_...
Check Whether a User Exists
...
You can also check user by id command.
id -u name gives you the id of that user.
if the user doesn't exist, you got command return value ($?)1
And as other answers pointed out: if all you want is just to check if the user exists, use if with id directl...