Lesson 06 · 12 min
CREATE TABLE: types and constraints
Rules in the table itself won't let garbage in, even if the app makes a mistake.
12 minLesson 6 of 10Practice includedAsk AI on any point
CREATE TABLE describes columns, their types, and constraints. PRIMARY KEY is the row's unique identifier. NOT NULL forbids empty values, UNIQUE forbids repeats, CHECK forbids values outside a rule, REFERENCES forbids links to a missing row. The database checks this on every write, so data stays consistent no matter who writes it or from where.
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