PostgreSQL/String Functions/substring

substring(name FROM 3 FOR 5)

postgres=# CREATE TABLE employee (
postgres(#     ID         int,
postgres(#     name       varchar(10),
postgres(#     salary     real,
postgres(#     start_date date,
postgres(#     city       varchar(10),
postgres(#     region     char(1)
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (1,  "Jason", 40420,  "02/01/94", "New York", "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (2,  "Robert",14420,  "01/02/95", "Vancouver","N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (3,  "Celia", 24020,  "12/03/96", "Toronto",  "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (4,  "Linda", 40620,  "11/04/97", "New York", "N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (5,  "David", 80026,  "10/05/98", "Vancouver","W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (6,  "James", 70060,  "09/06/99", "Toronto",  "N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (7,  "Alison",90620,  "08/07/00", "New York", "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (8,  "Chris", 26020,  "07/08/01", "Vancouver","N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (9,  "Mary",  60020,  "06/09/02", "Toronto",  "W");
INSERT 0 1
postgres=#
postgres=# select * from employee;
 id |  name  | salary | start_date |   city    | region
----+--------+--------+------------+-----------+--------
  1 | Jason  |  40420 | 1994-02-01 | New York  | W
  2 | Robert |  14420 | 1995-01-02 | Vancouver | N
  3 | Celia  |  24020 | 1996-12-03 | Toronto   | W
  4 | Linda  |  40620 | 1997-11-04 | New York  | N
  5 | David  |  80026 | 1998-10-05 | Vancouver | W
  6 | James  |  70060 | 1999-09-06 | Toronto   | N
  7 | Alison |  90620 | 2000-08-07 | New York  | W
  8 | Chris  |  26020 | 2001-07-08 | Vancouver | N
  9 | Mary   |  60020 | 2002-06-09 | Toronto   | W
(9 rows)
postgres=#
postgres=# SELECT name, substring(name FROM 3 FOR 5)
postgres-#         FROM employee
postgres-#         ORDER BY name DESC;
  name  | substring
--------+-----------
 Robert | bert
 Mary   | ry
 Linda  | nda
 Jason  | son
 James  | mes
 David  | vid
 Chris  | ris
 Celia  | lia
 Alison | ison
(9 rows)
postgres=#
postgres=#
postgres=#
postgres=# drop table employee;
DROP TABLE
postgres=#

substring(s FROM n FOR l): Returns a character sub-string of the character

postgres=# CREATE TABLE employee (
postgres(#     ID         int,
postgres(#     name       varchar(10),
postgres(#     salary     real,
postgres(#     start_date date,
postgres(#     city       varchar(10),
postgres(#     region     char(1)
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (1,  "Jason", 40420,  "02/01/94", "New York", "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (2,  "Robert",14420,  "01/02/95", "Vancouver","N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (3,  "Celia", 24020,  "12/03/96", "Toronto",  "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (4,  "Linda", 40620,  "11/04/97", "New York", "N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (5,  "David", 80026,  "10/05/98", "Vancouver","W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (6,  "James", 70060,  "09/06/99", "Toronto",  "N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (7,  "Alison",90620,  "08/07/00", "New York", "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (8,  "Chris", 26020,  "07/08/01", "Vancouver","N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (9,  "Mary",  60020,  "06/09/02", "Toronto",  "W");
INSERT 0 1
postgres=#
postgres=# select * from employee;
 id |  name  | salary | start_date |   city    | region
----+--------+--------+------------+-----------+--------
  1 | Jason  |  40420 | 1994-02-01 | New York  | W
  2 | Robert |  14420 | 1995-01-02 | Vancouver | N
  3 | Celia  |  24020 | 1996-12-03 | Toronto   | W
  4 | Linda  |  40620 | 1997-11-04 | New York  | N
  5 | David  |  80026 | 1998-10-05 | Vancouver | W
  6 | James  |  70060 | 1999-09-06 | Toronto   | N
  7 | Alison |  90620 | 2000-08-07 | New York  | W
  8 | Chris  |  26020 | 2001-07-08 | Vancouver | N
  9 | Mary   |  60020 | 2002-06-09 | Toronto   | W
(9 rows)
postgres=#
postgres=# -- substring(s FROM n FOR l): Returns a character sub-string of the character
postgres=# -- string s, starting at digit n (counting from 1), with optional maximum length l
postgres=# -- characters
postgres=#
postgres=# SELECT name, substring(name FROM 2)
postgres-#         FROM employee
postgres-#         ORDER BY name DESC
postgres-#         LIMIT 3;
  name  | substring
--------+-----------
 Robert | obert
 Mary   | ary
 Linda  | inda
(3 rows)
postgres=#
postgres=#
postgres=#
postgres=# drop table employee;
DROP TABLE
postgres=#

substring(string [from int] [for int]) bytea Extract substring

postgres=#
postgres=# -- substring(string [from int] [for int]) bytea Extract substring
postgres=# select substring("Th\\000omas"::bytea from 2 for 3);
 substring
-----------
 h\000o
(1 row)
postgres=#