What are constraints in SQL?

1.	What are constraints in SQL?
Answer» Constraints in SQL are the limits or rules that we can APPLY to the different types of data in a given table. Constraints are used to ensure the accuracy and RELIABILITY of the data in the table. The constraints in SQL are as follows: NOT NULL: This particular constraint informs us that ONE cannot store a null value within a column. UNIQUE: When specified with a column, this constraint informs that all the VALUES in a given column must be unique. PRIMARY KEY: A primary key is a field that can uniquely identify each row in a table. This is typically used to specify a field in a table as the primary key. FOREIGN KEY: A Foreign key is a field that can uniquely identify each row in another table. CHECK: This constraint helps us to validate the values of a column to attain a particular condition. DEFAULT: This constraint gives a default value for the column when the user does not specify a value.

Answer»

Constraints in SQL are the limits or rules that we can APPLY to the different types of data in a given table. Constraints are used to ensure the accuracy and RELIABILITY of the data in the table.

The constraints in SQL are as follows:

NOT NULL: This particular constraint informs us that ONE cannot store a null value within a column.
UNIQUE: When specified with a column, this constraint informs that all the VALUES in a given column must be unique.
PRIMARY KEY: A primary key is a field that can uniquely identify each row in a table. This is typically used to specify a field in a table as the primary key.
FOREIGN KEY: A Foreign key is a field that can uniquely identify each row in another table.
CHECK: This constraint helps us to validate the values of a column to attain a particular condition.
DEFAULT: This constraint gives a default value for the column when the user does not specify a value.

What are constraints in SQL?

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