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How to request a random row in SQL?
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See this post: SQL to Select a random row from a database table. It goes through methods for doing this in MySQL, PostgreSQL, Microsoft SQL Server, IBM DB2 and Oracle (the following is copied from that link):
Select a random row with MySQL:
SELECT column FROM table
ORDER BY RAND()...
Mapping many-to-many association table with extra column(s)
My database contains 3 tables:
User and Service entities have many-to-many relationship and are joined with the SERVICE_USER table as follows:
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Cannot delete or update a parent row: a foreign key constraint fails
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As is, you must delete the row out of the advertisers table before you can delete the row in the jobs table that it references. This:
ALTER TABLE `advertisers`
ADD CONSTRAINT `advertisers_ibfk_1` FOREIGN KEY (`advertiser_id`)
REFERENCES `jobs` (`advertiser_id`);
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CSS vertical alignment text inside li
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Define the parent with display: table and the element itself with vertical-align: middle and display: table-cell.
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MySQL JOIN the most recent row only?
I have a table customer that stores a customer_id, email and reference. There is an additional table customer_data that stores a historical record of the changes made to the customer, i.e. when there's a change made a new row is inserted.
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How Can I Set the Default Value of a Timestamp Column to the Current Timestamp with Laravel Migratio
... use DB::raw() to set CURRENT_TIMESTAMP as a default value for a column:
$table->timestamp('created_at')->default(DB::raw('CURRENT_TIMESTAMP'));
This works flawlessly on every database driver.
New shortcut
As of Laravel 5.1.25 (see PR 10962 and commit 15c487fe) you can use the new useCurr...
MySQL - UPDATE multiple rows with different values in one query
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You can do it this way:
UPDATE table_users
SET cod_user = (case when user_role = 'student' then '622057'
when user_role = 'assistant' then '2913659'
when user_role = 'admin' then '6160230'
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How do I import CSV file into a MySQL table?
...alized events-diary CSV from a client that I'm trying to load into a MySQL table so that I can refactor into a sane format. I created a table called 'CSVImport' that has one field for every column of the CSV file. The CSV contains 99 columns , so this was a hard enough task in itself:
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What are the performance characteristics of sqlite with very large database files? [closed]
...application).
The tests involve a single sqlite file with either a single table, or multiple tables. Each table had about 8 columns, almost all integers, and 4 indices.
The idea was to insert enough data until sqlite files were about 50GB.
Single Table
I tried to insert multiple rows into a sqli...
Table Naming Dilemma: Singular vs. Plural Names [closed]
Academia has it that table names should be the singular of the entity that they store attributes of.
41 Answers
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