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How do I make a column unique and index it in a Ruby on Rails migration?
... What is the best way to do it? Also is there a way to index a column in a table?
8 Answers
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How to center a checkbox in a table cell?
... contains nothing but a checkbox. It is rather wide because of text in the table header row. How do I center the checkbox (with inline CSS in my HTML? (I know))
...
How can I remove duplicate rows?
... is the best way to remove duplicate rows from a fairly large SQL Server table (i.e. 300,000+ rows)?
38 Answers
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SQL - Update multiple records in one query
I have table - config .
Schema:
config_name | config_value
9 Answers
9
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How to set a default value for a datetime column to record creation time in a migration?
Consider the table creation script below:
7 Answers
7
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Rails 3: Get Random Record
...ils 3 all examples will work. But using order RANDOM is quite slow for big tables but more sql-style
UPD. You can use the following trick on an indexed column (PostgreSQL syntax):
select *
from my_table
where id >= trunc(
random() * (select max(id) from my_table) + 1
)
order by id
limit 1...
How can I export the schema of a database in PostgreSQL?
...ed formats
--lock-wait-timeout=TIMEOUT fail after waiting TIMEOUT for a table lock
-?, --help show this help, then exit
Options controlling the output content:
-a, --data-only dump only the data, not the schema
-b, --blobs include large objec...
T-SQL: Selecting rows to delete via joins
...
DELETE TableA
FROM TableA a
INNER JOIN TableB b
ON b.Bid = a.Bid
AND [my filter condition]
should work
share
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MySQL - Rows to Columns
...e of terms that I'll use for the rest of this post. This will be the base table:
select * from history;
+--------+----------+-----------+
| hostid | itemname | itemvalue |
+--------+----------+-----------+
| 1 | A | 10 |
| 1 | B | 3 |
| 2 | A | ...
Hibernate error - QuerySyntaxException: users is not mapped [from users]
I'm trying to get a list of all the users from "users" table and I get the following error:
18 Answers
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