Why we need to use the Unique constraint in PostgreSQL And similar steps will be followed while updating the current data. When we have used the UNIQUE constraint, every time we insert a new row, it checks if the value is already in the table, rejects the modification and raise an error if the value already exists. The Roll numbers and the Email address should be the unique columns in the Student.The Phone number of clients should be a unique column in the Clients.Sometimes, if we want to ensure that values stored in a column or multiple columns are unique across the entire table, then a column cannot store duplicate values. If we add two different null values into a column in different rows, it does not interrupt the UNIQUE constraint's specification. When we are using the unique constraint, an index on one or more columns generate automatically. It is compatible with a group of column constraints or column constraints and a table constraint. In PostgreSQL, the UNIQUE CONSTRAINT is used to maintain the individuality of the values that we store into a field or a column of the table. What is PostgreSQL Unique key Constraint?
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In this section, we are going to understand the working of the PostgreSQL UNIQUE constraint, which is used to make sure that all values in a column of a table are exclusive.Įxamples of the PostgreSQL Unique constraint, how to create a unique constraint on multiple columns, adding a unique constraint using a unique index, and also see how to drop a unique constraint for the particular table. Next → ← prev PostgreSQL Unique Constraint
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