Key Concepts

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Column Constraints

CREATE TABLE student ( id INTEGER PRIMARY KEY, name TEXT UNIQUE, grade INTEGER NOT NULL, age INTEGER DEFAULT 10 );

Column constraints are the rules applied to the values of individual columns:

  • PRIMARY KEY constraint can be used to uniquely identify the row.
  • UNIQUE columns have a different value for every row.
  • NOT NULL columns must have a value.
  • DEFAULT assigns a default value for the column when no value is specified.

There can be only one PRIMARY KEY column per table and multiple UNIQUE columns.

Manipulation
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