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How to copy a row and insert in same table with a autoincrement field in MySQL?
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Use INSERT ... SELECT:
insert into your_table (c1, c2, ...)
select c1, c2, ...
from your_table
where id = 1
where c1, c2, ... are all the columns except id. If you want to explicitly insert with an id of 2 then include that in your INSER...
Joining two lists together
...eserves the order of the lists, but it doesn't remove any duplicates which Union would do.
This does change list a. If you wanted to preserve the original lists then you should use Concat (as pointed out in the other answers):
var newList = a.Concat(b);
This returns an IEnumerable as long as a i...
What is the “N+1 selects problem” in ORM (Object-Relational Mapping)?
The "N+1 selects problem" is generally stated as a problem in Object-Relational mapping (ORM) discussions, and I understand that it has something to do with having to make a lot of database queries for something that seems simple in the object world.
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MySQL and GROUP_CONCAT() maximum length
...You should use it like this.
SET SESSION group_concat_max_len = 1000000;
select group_concat(column) from table group by column
You can do this even in sharing hosting, but when you use an other session, you need to repeat the SET SESSION command.
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Why does MYSQL higher LIMIT offset slow the query down?
...h more than 16 million records [2GB in size]. The higher LIMIT offset with SELECT, the slower the query becomes, when using ORDER BY *primary_key*
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How to create relationships in MySQL
...s defined as the default storage engine,can check using command (mysql> SELECT @@default_storage_engine;)
– Arun
Feb 18 at 4:00
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Remote Connections Mysql Ubuntu
For some reason, I've been unable to connect remotely to my MySQL server. I've tried everything and I'm still getting errors.
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MySQL error: key specification without a key length
...d, and the trick is to choose a number N that’s long enough to give good selectivity, but short enough to save space. The prefix should be long enough to make the index nearly as useful as it would be if you’d indexed the whole column.
Before we go further let us define some important terms. In...
How to run Django's test database only in memory?
...s line: 'ENGINE': 'sqlite3' if 'test' in sys.argv else 'django.db.backends.mysql',
– mjallday
Jan 19 '11 at 6:26
3
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Remove duplicate rows in MySQL
...ate temporary table tmpTable (id int);
insert into tmpTable
(id)
select id
from YourTable yt
where exists
(
select *
from YourTabe yt2
where yt2.title = yt.title
and yt2.company = yt.company
and yt2.site_id = yt.si...