sqlite

create table:

CREATE TABLE child ( 
    id           INTEGER PRIMARY KEY, 
    parent_id    INTEGER, 
    description  TEXT,
    FOREIGN KEY (parent_id) REFERENCES parent(id)
);

• make backup: sqlite3 /path/to/db '.backup /path/to/backup'
• add column with reference: alter table table_name add COLUMN column_name integer REFERENCES other_table(other_table_column_name));
• turn on wal mode: PRAGMA journal_mode=WAL;