Top "Unique-constraint" questions

Unique-constraint is an index that sets one or multiple fields to be unique in a data entity

How do I specify unique constraint for multiple columns in MySQL?

I have a table: table votes ( id, user, email, address, primary key(id), ); Now I want to make the columns …

mysql unique-constraint composite-key database-table
@UniqueConstraint annotation in Java

I have a Java bean. Now, I want to be sure that the field should be unique. I am using …

java jpa unique-constraint
How can I create a unique constraint on my column (SQL Server 2008 R2)?

I have SQL Server 2008 R2 and I want to set a unique column. There seems to be two ways to …

sql sql-server sql-server-2008 unique-constraint
Can I add a UNIQUE constraint to a PostgreSQL table, after it's already created?

I have the following table: tickername | tickerbbname | tickertype ------------+---------------+------------ USDZAR | USDZAR Curncy | C EURCZK | EURCZK Curncy | C EURPLN | …

sql database postgresql indexing unique-constraint
MySQL - Make an existing Field Unique

I have an already existing table with a field that should be unique but is not. I only know this …

mysql unique-constraint
How do I ALTER a PostgreSQL table and make a column unique?

I have a table in PostgreSQL where the schema looks like this: CREATE TABLE "foo_table" ( "id" serial NOT NULL …

sql postgresql unique-constraint
MySQL delete multiple rows in one query conditions unique to each row

So I know in MySQL it's possible to insert multiple rows in one query like so: INSERT INTO table (col1,…

mysql unique-constraint multiple-records
Does MySQL ignore null values on unique constraints?

I have an email column that I want to be unique. But I also want it to accept null values. …

mysql database unique-constraint
How to drop a unique constraint from table column?

I have a table 'users' with 'login' column defined as: [login] VARCHAR(50) UNIQUE NOT NULL Now I want to remove …

sql database sql-server-2005 unique-constraint non-clustered-index
Unique constraint violation during insert: why? (Oracle)

I'm trying to create a new row in a table. There are two constraints on the table -- one is …

oracle unique-constraint