psql -U your_username -d your_database_name <<EOF
DO $$
DECLARE
    i INT;
    j INT;
    create_table_sql TEXT;
    add_fk_sql TEXT;
BEGIN
    -- Create 10 tables
    FOR i IN 1..10 LOOP
        create_table_sql := format('
            CREATE TABLE table%s (
                id SERIAL PRIMARY KEY,
                data TEXT
            )', i);
        EXECUTE create_table_sql;
    END LOOP;

    -- Add foreign key constraints between each pair of tables
    FOR i IN 1..10 LOOP
        FOR j IN (i + 1)..10 LOOP
            -- Add foreign key from table i to table j
            add_fk_sql := format('
                ALTER TABLE table%s
                ADD CONSTRAINT fk_table%s_to_table%s
                FOREIGN KEY (id) REFERENCES table%s (id)
            ', i, i, j, j);
            EXECUTE add_fk_sql;
            
            -- Add foreign key from table j to table i
            add_fk_sql := format('
                ALTER TABLE table%s
                ADD CONSTRAINT fk_table%s_to_table%s
                FOREIGN KEY (id) REFERENCES table%s (id)
            ', j, j, i, i);
            EXECUTE add_fk_sql;
        END LOOP;
    END LOOP;
END $$;
EOF