The UNIQUE constraint ensures that all values in a column are different. Both the UNIQUE and PRIMARY KEY constraints provide a guarantee for uniqueness for a column or set of columns.

In SQL, the UNIQUE constraint in a column means that the column must have a unique value. In this tutorial, you will learn about the SQL UNIQUE constraint with the help of examples.

Mar 7, 2025 · The SQL UNIQUE constraint is an essential tool for ensuring data integrity and consistency within a database. By enforcing uniqueness in specific columns or combinations …

There are 4 methods you can use: Consider the following sample TABLE with test data: ,('bbb', 200, 2) ,('ccc', 300, 3) ,('bbb', 400, 4) ,('bbb', 200, 5) -- duplicate. ,('ccc', 300, 6) -- duplicate. …

Feb 4, 2021 · By using a UNIQUE constraint on a particular column, we ensure that this column cannot contain two of the same values. Let’s see an example using the Person table with the …

Mar 3, 2024 · Implementing SQL UNIQUE constraints plays a significant role in this, as it directly impacts the integrity by preventing duplicate entries in a database table. Let’s consider a …

The UNIQUE Constraint prevents two records from having identical values in a column. In the CUSTOMERS table, for example, you might want to prevent two or more people from having …

SQL unique constraint is a type of constraint that ensures that the data in a column or set of columns is unique across all rows in a table. It is used to prevent duplicate values from being …

We would like to make the column name unique in the table product. The query below presents one way to do it. In this example a given column (the column name) was made unique by …

What is SQL UNIQUE? A UNIQUE constraint in SQL is a database constraint that ensures the uniqueness of values in one or more columns within a table. It guarantees that all values in the …