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@@ -189,25 +189,25 @@ These components are −
Following are some of the most commonly used constraints available in SQL − Following are some of the most commonly used constraints available in SQL −
### NOT NULL Constraint ### !) NOT NULL Constraint
− Ensures that a column cannot have a NULL value. − Ensures that a column cannot have a NULL value.
### DEFAULT Constraint ### 2) DEFAULT Constraint
− Provides a default value for a column when none is specified. − Provides a default value for a column when none is specified.
### UNIQUE Constraint ### 3) UNIQUE Constraint
− Ensures that all the values in a column are different. − Ensures that all the values in a column are different.
### PRIMARY Key ### 4) PRIMARY Key
− Uniquely identifies each row/record in a database table. − Uniquely identifies each row/record in a database table.
### FOREIGN Key ### 5) FOREIGN Key
− Uniquely identifies a row/record in any another database table. − Uniquely identifies a row/record in any another database table.
### CHECK Constraint ### 6) CHECK Constraint
− The CHECK constraint ensures that all values in a column satisfy certain conditions. − The CHECK constraint ensures that all values in a column satisfy certain conditions.
### INDEX ### 7) INDEX
− Used to create and retrieve data from the database very quickly. − Used to create and retrieve data from the database very quickly.
# Data Integrity 🚧 # Data Integrity 🚧