Mega Code Archive

Using the FOR loop with %ROWTYPE

postgres=# postgres=# postgres=# CREATE TABLE "books" ( postgres(# "id" integer NOT NULL, postgres(# "title" text NOT NULL, postgres(# "author_id" integer, postgres(# "subject_id" integer, postgres(# Constraint "books_id_pkey" Primary Key ("id") postgres(# ); NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "books_id_pkey" for table "books" CREATE TABLE postgres=# postgres=# postgres=# insert into books values (7808, 'Java', 4156, 9); INSERT 0 1 postgres=# insert into books values (4513, 'Javascript', 1866, 15); INSERT 0 1 postgres=# insert into books values (4267, 'C#', 2001, 15); INSERT 0 1 postgres=# insert into books values (1608, 'Oracle', 1809, 2); INSERT 0 1 postgres=# insert into books values (1590, 'Sql Server', 1809, 2); INSERT 0 1 postgres=# insert into books values (25908, 'Postgre SQL', 15990, 2); INSERT 0 1 postgres=# insert into books values (1501, 'Python', 2031, 2); INSERT 0 1 postgres=# insert into books values (190, 'Java by API', 16, 6); INSERT 0 1 postgres=# insert into books values (1234, '2D', 25041, 3); INSERT 0 1 postgres=# insert into books values (2038, 'C', 1644, 0); INSERT 0 1 postgres=# insert into books values (156, 'C++', 115, 9); INSERT 0 1 postgres=# insert into books values (41473, 'Programming Python', 7805, 4); INSERT 0 1 postgres=# insert into books values (41477, 'Learning Python', 7805, 4); INSERT 0 1 postgres=# insert into books values (41478, 'Perl Cookbook', 7806, 4); INSERT 0 1 postgres=# insert into books values (41472, 'Practical PostgreSQL', 1212, 4); INSERT 0 1 postgres=# postgres=# select * from books; id | title | author_id | subject_id -------+----------------------+-----------+------------ 7808 | Java | 4156 | 9 4513 | Javascript | 1866 | 15 4267 | C# | 2001 | 15 1608 | Oracle | 1809 | 2 1590 | Sql Server | 1809 | 2 25908 | Postgre SQL | 15990 | 2 1501 | Python | 2031 | 2 190 | Java by API | 16 | 6 1234 | 2D | 25041 | 3 2038 | C | 1644 | 0 156 | C++ | 115 | 9 41473 | Programming Python | 7805 | 4 41477 | Learning Python | 7805 | 4 41478 | Perl Cookbook | 7806 | 4 41472 | Practical PostgreSQL | 1212 | 4 (15 rows) postgres=# postgres=# postgres=# -- Using the FOR loop with %ROWTYPE postgres=# postgres=# CREATE FUNCTION extract_title (integer) RETURNS text AS ' postgres'# DECLARE postgres'# postgres'# -- Declare an alias for function argument. postgres'# sub_id ALIAS FOR $1; postgres'# postgres'# -- Declare a variable to hold book titles and set its default postgres'# -- value to a new line. postgres'# text_output TEXT :=''\n''; postgres'# postgres'# -- Declare a variable to hold rows from the postgres'# -- books table. postgres'# row_data books%ROWTYPE; postgres'# postgres'# BEGIN postgres'# postgres'# -- Iterate through the results of a query. postgres'# FOR row_data IN SELECT * FROM books postgres'# WHERE subject_id = sub_id ORDER BY title LOOP postgres'# postgres'# -- Insert the title of a matching book into the text_output variable. postgres'# text_output := text_output || row_data.title || ''\n''; postgres'# END LOOP; postgres'# postgres'# -- Return the list of books. postgres'# RETURN text_output; postgres'# END; postgres'# ' LANGUAGE 'plpgsql'; ERROR: function "extract_title" already exists with same argument types postgres=# postgres=# postgres=# SELECT extract_title(2); extract_title --------------- Sql Server (1 row) postgres=# postgres=# postgres=# drop table books; DROP TABLE postgres=# postgres=#