If so - What must change in this table ? CREATE TABLE contestants ( idContestants int(10) unsigned NOT NULL AUTO_INCREMENT, idEvent int(10) unsigned NOT NULL, ContestantName varchar(50) DEFAU...

How can I check whether a field from a table is set as UNIQUE? For example I have a table named users with a field email set as UNIQUE and a field picture not set as UNIQUE, I want before selectin...

I'm using Microsoft SQL Server 2008 R2 (with latest service pack/patches) and the database collation is SQL_Latin1_General_CP1_CI_AS. The following code: SET ANSI_PADDING ON; GO CREATE TABLE Test ...

I've been trying to sort out the relationship between unique and index in Postgres after reading the docs on index uniqueness being an implementation detail: The preferred way to add a unique co...

I have a portion of simple code, that has to fail because of unique index constraint. But both of the objects are added to database and can be queried, in spite of unique index. BasicDBObject typ...

I have 3 columns (_id, column1, column2) _id column has been set as autoincrement In database there are some duplicate records, so I want to prevent duplicate records with setting column1 as uniqu...

I need to add a unique field index to an existing table. I made this row: ALTER TABLE auth_user ADD UNIQUE INDEX (email); The table and the field are already exist. The error is: Query Error...

I have a table that stores comments users make about images on the site. The table is structured with four columns, the row_id, which is the primary key, the image_id, the user_id and the comment. ...

I've got a MySQL table that stores urls as unique keys. I'm starting to get collisions on my keys because it seems the keys themselves are only the first 64 bytes (or characters if you prefer, its ...

On one of my PostgreSQL tables, I have a set of two fields that will be defined as being unique in the table, but will also both be used together when selecting data. Given this, do I only need to ...

Why does INDEX creation statement have UNIQUE argument? As I understand, the non-clustered index contains a bookmark, a pointer to a row, which should be unique to distinguish even non-unique rows...

Below is the use case: I have a unique index defined on 3 columns say A,B,C. Assume the values in them are A1,B1,C1. My java code is adding a new record say A1,B1,C1 but before this record is added...

I have the following in my migration file def self.up create_table :payment_agreements do |t| t.boolean :automatic, :default => true, :null => false t.string :payment_trigger_on_order t...

Here's a little experiment I ran in an Oracle database (10g). Aside from (Oracle's) implementation convenience, I can't figure out why some insertions are accepted and others rejected. create tabl...

Often when I define a View in Navicat I receive the following message: xxx does not have a primary key. Updates to this table will be done using the following pseudo statement: UPDATE xxx SET Mo...

I have the following table structure CREATE TABLE `table` ( `id` int(11) NOT NULL auto_increment, `date_expired` datetime NOT NULL, `user_id` int(11) NOT NULL, `foreign_id` int(11) NOT NULL, ...

I have a field in a database that is nearly unique: 98% of the time the values will be unique, but it may have a few duplicates. I won't be doing many searches on this field; say twice a month. The...