Explain, please, what do the lines of sql query in h2 database mean?

Question

SQL

What do these queries mean:
constraint uq_user_email_address unique (email_address),
constraint pk_user primary key (id))
UPD:
also create sequence todo_seq;
Thank you)

Answer 1

create sequence - create a sequence with the specified name. Used in many DBMS to implement auto-increment for any column (most often our favorite ID).