大约有 19,000 项符合查询结果（耗时：0.0299秒） [XML]
Check if object value exists within a Javascript array of objects and if not add a new object to arr
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I've assumed that ids are meant to be unique here. some is a great function for checking the existence of things in arrays:
const arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { id: 3, username: 'ted' }];
function ad...
MySQL select 10 random rows from 600K rows fast
...m AS r1 JOIN
(SELECT CEIL(RAND() *
(SELECT MAX(id)
FROM random)) AS id)
AS r2
WHERE r1.id >= r2.id
ORDER BY r1.id ASC
LIMIT 1
This supposes that the distribution of ids is equal, and that there can be gaps in the id list. See the ar...
When use getOne and findOne methods Spring Data JPA
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TL;DR
T findOne(ID id) (name in the old API) / Optional<T> findById(ID id) (name in the new API) relies on EntityManager.find() that performs an entity eager loading.
T getOne(ID id) relies on EntityManager.getReference() that perform...
How to find largest objects in a SQL Server database?
...ceMB
FROM
sys.tables t
INNER JOIN
sys.indexes i ON t.object_id = i.object_id
INNER JOIN
sys.partitions p ON i.object_id = p.object_id AND i.index_id = p.index_id
INNER JOIN
sys.allocation_units a ON p.partition_id = a.container_id
WHERE
t.name NOT LIKE 'dt%' AND
i.o...
Real life example, when to use OUTER / CROSS APPLY in SQL
... FROM sys.parameters pa
WHERE pa.object_id = pr.object_id
ORDER BY pr.name) pa
ORDER BY pr.name,
pa.name
2) Calling a Table Valued Function for each row in the outer query
SELECT *
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY s...
Showing empty view when ListView is empty
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It should be like this:
<TextView android:id="@android:id/empty"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="No Results" />
Note the id attribute.
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What is the id( ) function used for?
I read the Python 2 docs and noticed the id() function:
13 Answers
13
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SQL server query to get the list of columns in a table along with Data types, NOT NULL, and PRIMARY
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To avoid duplicate rows for some columns, use user_type_id instead of system_type_id.
SELECT
c.name 'Column Name',
t.Name 'Data type',
c.max_length 'Max Length',
c.precision ,
c.scale ,
c.is_nullable,
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SQL WHERE ID IN (id1, id2, …, idn)
I need to write a query to retrieve a big list of ids.
9 Answers
9
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Many-to-many relationship with the same model in rails?
...the schema for that:
create_table "post_connections", :force => true, :id => false do |t|
t.integer "post_a_id", :null => false
t.integer "post_b_id", :null => false
end
By default, Rails will call this table a combination of the names of the two tables we're joining. But that wou...