The syntax is: a[start:stop] # items start through stop-1 a[start:] # items start through the rest of the array a[:stop] # items from the beginning through stop-1 a[:] # a copy of the whole array There is also the step value, which can be used with any of the above: a[start:stop:step] # start through not … Read more
Yes: list1 + list2. This gives a new list that is the concatenation of list1 and list2.
Yes, SQL 11 has SEQUENCE objects, see SQL Server v.Next (Denali) : Using SEQUENCE. Creating manual sequences is possible, but not recommended. The trick to do a sequence generator is to use UPDATE WITH OUTPUT on a sequences table. Here is pseudo-code: CREATE TABLE Sequences ( Name sysname not null primary key, Sequence bigint not … Read more
Just update your trigger to only fire when not given an id. create or replace trigger sa.my_trigger before insert on sa.my_table for each row when (new.id is null) begin select sa.my_sequence.nextval into :new.id from dual; end;
RETURNING That’s possible with a single round-trip to the database: INSERT INTO tbl(filename) VALUES (‘my_filename’) RETURNING tbl_id; tbl_id would typically be a serial or IDENTITY (Postgres 10 or later) column. More in the manual. Explicitly fetch value If filename needs to include tbl_id (redundantly), you can still use a single query. Use lastval() or the … Read more
It turned out to be easy enough: create table mytable ( id bigint not null constraint DF_mytblid default next value for mainseq, code varchar(20) not null ) or if the table is already created: alter table mytable add constraint DF_mytblid default next value for mainseq for id (thank you Matt Strom for the correction!)
Yes, it is possible. You can override the default generator name with the @SequenceGenerator annotation. Base class @MappedSuperclass public abstract class PersistentEntity implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = “default_gen”) protected Long id = 0L; public Long getId() { return id; } public void setId(Long id) … Read more
Use itertools.product. from string import ascii_lowercase import itertools def iter_all_strings(): for size in itertools.count(1): for s in itertools.product(ascii_lowercase, repeat=size): yield “”.join(s) for s in iter_all_strings(): print(s) if s == ‘bb’: break Result: a b c d e … y z aa ab ac … ay az ba bb This has the added benefit of going … Read more