Should constraint names be unique?

Constraint names must be unique within a schema.

How can we define constraints with user defined name?

Constraints can be specified when the table created first with CREATE TABLE statement or at the time of modification of the structure of an existing table with ALTER TABLE statement. The CONSTRAINT keyword is followed by a constraint name followed by a column or a list of columns.

How do you name a constraint in SQL?

To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: ALTER TABLE Sales ADD CONSTRAINT PK_ Sales PRIMARY KEY (Sale_Id,Sale_Amount);

How do you name a unique constraint?

The naming conventions for unique key constraints should have a “UQ_” prefix, followed by the table name, followed by the column name. The syntax for a unique constraint should be “UQ__”.

Can foreign keys have the same name?

There is no issue having the primary key of table A be the same name as the foreign key of table B that relates to it.

How do you create a constraint name?

To add a primary key constraint to a table, you should explicitly define the primary key at table creation. To replace an existing primary key, you can use ADD CONSTRAINT PRIMARY KEY ….The ADD CONSTRAINT statement is part of ALTER TABLE and can add the following constraints to columns:

UNIQUE.
CHECK.
FOREIGN KEY.

What are the five table constraints in Oracle?

Oracle Constraints Examples

NOT Null Constraint. NOT NULL column must have a value.
UNIQUE Constraint. UNIQUE Constraint column should have either unique values or null values across the table.
Primary Key Constraint.
Foreign Key Constraint.
CHECK Constraint.

Which clause will allow you to disable a constraint?

Use the DROP CONSTRAINT clause to destroy an existing constraint whose name you specify. This syntax fragment is part of the ALTER TABLE statement.