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Get top 1 row of each group
I have a table which I want to get the latest entry for each group. Here's the table:
20 Answers
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How to persist a property of type List in JPA?
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@Please_Dont_Bully_Me_SO_Lords It is less suitable for that use case since your data will be in the database as "foo;bar;foobar". If you want to query for the data then probably an ElementCollection + JoinTable is the way to go for your situation.
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PostgreSQL naming conventions
Where can I find a detailed manual about PostgreSQL naming conventions? (table names vs. camel case, sequences, primary keys, constraints, indexes, etc...)
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How do I create a PDO parameterized query with a LIKE statement?
...t out right after I posted:
$query = $database->prepare('SELECT * FROM table WHERE column LIKE ?');
$query->execute(array('value%'));
while ($results = $query->fetch())
{
echo $results['column'];
}
share
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How to generate an entity-relationship (ER) diagram using Oracle SQL Developer
I want to use Oracle SQL Developer to generate an ER diagram for my DB tables but I am new to Oracle and this tool.
8 Answe...
ORA-00054: resource busy and acquire with NOWAIT specified or timeout expired
Why am I getting this database error when I update a table?
14 Answers
14
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First-time database design: am I overengineering? [closed]
...ds. Unless you are talking about well over a million records in your main tables you seem to be on track to having a sufficiently mainstream design that performance will not be an issue on reasonable hardware.
That said, and this relates to your question 3, with the start you have you probably s...
T-SQL: Deleting all duplicate rows but keeping one [duplicate]
I have a table with a very large amount of rows. Duplicates are not allowed but due to a problem with how the rows were created I know there are some duplicates in this table.
I need to eliminate the extra rows from the perspective of the key columns. Some other columns may have slightly different...
MySQL high CPU usage [closed]
... time, and use that to make sure you don't have any queries locking up key tables for too long.
Some other things you can check would be to run the following query while the CPU load is high:
SHOW PROCESSLIST;
This will show you any queries that are currently running or in the queue to run, what...
Rails: Using greater than/less than with a where statement
...non discrete values or columns where you can't use the + 1 strategy.
Arel table
If you want to get fancy you can make use of the Arel::Table.
User.where(User.arel_table[:id].gt(200))
will generate the SQL
"SELECT `users`.* FROM `users` WHERE (`users`.`id` > 200)"
The specifics are as foll...