大约有 43,000 项符合查询结果（耗时：0.0359秒） [XML]
android get all contacts
... ContactsContract.Contacts.DISPLAY_NAME
} ;
String selection = null; //Selection criteria
String[] selectionArgs = {}; //Selection criteria
String sortOrder = null; //T...
Does the join order matter in SQL?
...t matter. The queries will return same results, as long as you change your selects from SELECT * to SELECT a.*, b.*, c.*.
For (LEFT, RIGHT or FULL) OUTER joins, yes, the order matters - and (updated) things are much more complicated.
First, outer joins are not commutative, so a LEFT JOIN b is no...
When should I use semicolons in SQL Server?
...llowing two queries (copied from this post):
BEGIN TRY
BEGIN TRAN
SELECT 1/0 AS CauseAnException
COMMIT
END TRY
BEGIN CATCH
SELECT ERROR_MESSAGE()
THROW
END CATCH
BEGIN TRY
BEGIN TRAN
SELECT 1/0 AS CauseAnException;
COMMIT
END TRY
BEGIN CATCH
SELECT ERROR_MES...
Why is using the rails default_scope often recommend against?
...ate) posts. So far so good.
2.1.1 :001 > Post.all
Post Load (0.2ms) SELECT "posts".* FROM "posts" WHERE "posts"."published" = 't'
Well this is pretty much what we expect. Now lets try:
2.1.1 :004 > Post.new
=> #<Post id: nil, title: nil, published: true, created_at: nil, update...
LINQ with groupby and count
...(var line in data.GroupBy(info => info.metric)
.Select(group => new {
Metric = group.Key,
Count = group.Count()
})
.OrderBy(x => x.Metric))
{
Console.Wri...
Are Stored Procedures more efficient, in general, than inline statements on modern RDBMS's? [duplica
...he query plan that is generated is sub-optimal.
For example, if you send SELECT *
FROM table WHERE id BETWEEN 1 AND
99999999, the DBMS may select a
full-table scan instead of an index
scan because you're grabbing every row
in the table (so sayeth the
statistics). If this is the cached
...
Sequence contains no elements?
...in dc.BlogPosts
where p.BlogPostID == id
select p).Single();
Also; if this is LINQ-to-SQL, then in the current version you get a slightly better behaviour if you use the form:
var id = ID;
BlogPost post = dc.BlogPosts.Single(p => p.BlogPostID == id);
...
Delete all records in a table of MYSQL in phpMyAdmin
...ampserver 2.2. When I want to delete all records of a table in phpMyAdmin (select all) it deletes only one record not all records. Why it does not delete all records?
...
How to apply two CSS classes to a single element
...To target elements that contain all of the specified classes, use this CSS selector (no space) (ref):
.c1.c2 {
}
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Parallel.ForEach() vs. foreach(IEnumerable.AsParallel())
...the AsParallel() call, like:
var fibonacciNumbers = numbers.AsParallel().Select(n => ComputeFibonacci(n));
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