大约有 48,000 项符合查询结果（耗时：0.0423秒） [XML]
SQL Query Where Field DOES NOT Contain $x
...t is meant to be used in subqueries or with predefined lists:
-- subquery
SELECT a FROM x WHERE x.b NOT IN (SELECT b FROM y);
-- predefined list
SELECT a FROM x WHERE x.b NOT IN (1, 2, 3, 6);
If you are searching a string, go for the LIKE operator (but this will be slow):
-- Finds all rows where...
MySQL Data - Best way to implement paging?
...e LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants (except when using prepared statements).
With two arguments, the first argument specifies the offset of the first ro...
phpunit mock method multiple calls with different arguments
... ->with($this->logicalOr(
$this->equalTo('select * from roles'),
$this->equalTo('select * from users')
))
->will($this->returnCallback(array($this, 'myCallback')));
var_dump($mock->Query("select * from us...
Why do we always prefer using parameters in SQL statements?
I am very new to working with databases. Now I can write SELECT , UPDATE , DELETE , and INSERT commands. But I have seen many forums where we prefer to write:
...
convert a list of objects from one type to another using lambda expression
...
Try the following
var targetList = origList
.Select(x => new TargetType() { SomeValue = x.SomeValue })
.ToList();
This is using a combination of Lambdas and LINQ to achieve the solution. The Select function is a projection style method which will apply the passe...
How to add column if not exists on PostgreSQL?
...s, _col text, _type regtype)
RETURNS bool AS
$func$
BEGIN
IF EXISTS (SELECT 1 FROM pg_attribute
WHERE attrelid = _tbl
AND attname = _col
AND NOT attisdropped) THEN
RETURN FALSE;
ELSE
EXECUTE format('ALTER TABLE %s ADD COLUMN %I %s...
Search text in fields in every table of a MySQL database
...
If you have phpMyAdmin installed use its 'Search' feature.
Select your DB
Be sure you do have a DB selected (i.e. not a table, otherwise you'll get a completely different search dialog)
Click 'Search' tab
Choose the search term you want
Choose the tables to search
I have used this ...
LINQ's Distinct() on a particular property
...
(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
HashSet<TKey> seenKeys = new HashSet<TKey>();
foreach (TSource element in source)
{
if (seenKeys.Add(keySelector(element)))
{
yield return element;
}
...
Drop data frame columns by name
...op=FALSE to keep R from converting your data frame to a vector if you only select a single column. Don't forget that data frames are lists, so list selection (one-dimensional like I did) works perfectly well and always returns a list. Or a data frame in this case, which is why I prefer to use it.
...
SQL Server Linked Server Example Query
...a Linked Server in SSMS Object Explorer, right-click, and Script Table as, SELECT To, and New Query Editor Window. The resulting SELECT statement will include the correct, fully-qualified path to the table. I had a mystery database qualifier in working with Sybase and this gave me the correct name.
...