Vol. I · A Postgres Handbook

The Query & the Schema

A reading-room reference for writing PostgreSQL by hand — selects to window functions, with the schema in plain view.

IntermediateBasic SELECT

Constraint Practice: Add CHECK constraint variant #35

The query

SQL
ALTER TABLE practice_table_35
ADD CONSTRAINT chk_data_35 CHECK (LENGTH(data_value) > 3);
Tested against PostgreSQL 16

Note

“Ensuring data integrity through check constraints (Pattern #35).