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selecting unique values from a column
I have a MySQL table which contains the following type of information:
9 Answers
9
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How do I stop Entity Framework from trying to save/insert child objects?
...everything, EF seems to be still trying to insert into some of the related tables. At this point, I'm ready to rip EF out and switch back to SQL which at least behaves sensibly. What a pain.
– Mark Micallef
Aug 22 '14 at 8:29
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Which SQL query is faster? Filter on Join criteria or Where clause?
...LEFT JOIN.
In your very case this will look like this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAID = a.ID
AND a.ID = 1
LEFT JOIN
TableB b
ON x.TableBID = b.ID
or this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAI...
differentiate null=True, blank=True in django
...e)
The database fields created for PostgreSQL 9.4 are :
CREATE TABLE Test (
id serial NOT NULL,
"charNull" character varying(10),
"charBlank" character varying(10) NOT NULL,
"charNullBlank" character varying(10),
"intNull" in...
SQL Server: Maximum character length of object names
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Yes, it is 128, except for temp tables, whose names can only be up to 116 character long.
It is perfectly explained here.
And the verification can be easily made with the following script contained in the blog post before:
DECLARE @i NVARCHAR(800)
SELECT ...
Export and Import all MySQL databases at one time
...-databases > alldb.sql
mysqldump -u root -p --all-databases --skip-lock-tables > alldb.sql
Import:
mysql -u root -p < alldb.sql
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Delete/Reset all entries in Core Data?
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You can delete the SQLite file - but I choose to do it by purging the tables individually with a functions:
- (void) deleteAllObjects: (NSString *) entityDescription {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription enti...
Performance of FOR vs FOREACH in PHP
..._arr1 = array();
$test_arr2 = array();
$test_arr3 = array();
// hash tables
$test_arr4 = array();
$test_arr5 = array();
for ($i = 0; $i < $test_arr_size; ++$i)
{
mt_srand();
$hash = md5(mt_rand());
$key = substr($hash, 0, 5).$i;
$test_arr1[$i] = $test_arr2[$i] = $t...
How can I prevent the scrollbar overlaying content in IE10?
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This issue is also happening with Datatables on Bootstrap 4. Mi solution was:
Checked if the ie browser is opening.
Replaced table-responsive class for table-responsive-ie class.
CSS:
.table-responsive-ie {
display: block;
width: 100%;
overflow-x: auto;}
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