PostgreSQL/Postgre SQL/For
Nested for loop
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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=# CREATE TABLE "subjects" ( postgres(# "id" integer NOT NULL, postgres(# "subject" text, postgres(# "location" text, postgres(# Constraint "subjects_pkey" Primary Key ("id") postgres(# ); NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "subjects_pkey" for table "subjects" CREATE TABLE postgres=# postgres=# insert into subjects values (0, "Arts", "Creativity St"); INSERT 0 1 postgres=# insert into subjects values (1, "Business", "Productivity Ave"); INSERT 0 1 postgres=# insert into subjects values (2, "Children", "Books Kids Ct"); INSERT 0 1 postgres=# insert into subjects values (3, "Classics", "Academic Rd"); INSERT 0 1 postgres=# insert into subjects values (4, "Computers", "Productivity Ave"); INSERT 0 1 postgres=# insert into subjects values (5, "Cooking", "Creativity St"); INSERT 0 1 postgres=# insert into subjects values (6, "Drama", "Main St"); INSERT 0 1 postgres=# insert into subjects values (7, "Entertainment", "Main St"); INSERT 0 1 postgres=# insert into subjects values (8, "History", "Academic Rd"); INSERT 0 1 postgres=# insert into subjects values (9, "Horror", "Black Raven Dr"); INSERT 0 1 postgres=# insert into subjects values (10, "Mystery", "Black Raven Dr"); INSERT 0 1 postgres=# insert into subjects values (11, "Poetry", "Sunset Dr"); INSERT 0 1 postgres=# insert into subjects values (12, "Religion", "Regina"); INSERT 0 1 postgres=# insert into subjects values (13, "Romance", "Main St"); INSERT 0 1 postgres=# insert into subjects values (14, "Science", "Productivity Ave"); INSERT 0 1 postgres=# insert into subjects values (15, "Science Fiction", "Main St"); INSERT 0 1 postgres=# postgres=# select * from subjects;
id | subject | location
+-----------------+------------------
0 | Arts | Creativity St 1 | Business | Productivity Ave 2 | Children | Books Kids Ct 3 | Classics | Academic Rd 4 | Computers | Productivity Ave 5 | Cooking | Creativity St 6 | Drama | Main St 7 | Entertainment | Main St 8 | History | Academic Rd 9 | Horror | Black Raven Dr 10 | Mystery | Black Raven Dr 11 | Poetry | Sunset Dr 12 | Religion | Regina 13 | Romance | Main St 14 | Science | Productivity Ave 15 | Science Fiction | Main St
(16 rows) postgres=# postgres=# postgres=# postgres=# drop function extract_all_titles2(); DROP FUNCTION postgres=# postgres=# CREATE FUNCTION "extract_all_titles2" () RETURNS text AS " postgres"# DECLARE postgres"# sub_id INTEGER; postgres"# text_output TEXT = "" ""; postgres"# sub_title TEXT; postgres"# row_data books%ROWTYPE; postgres"# BEGIN postgres"# FOR i IN 0..15 LOOP postgres"# SELECT INTO sub_title subject FROM subjects WHERE id = i; postgres"# text_output = text_output || """" || sub_title || "":""; postgres"# postgres"# FOR row_data IN SELECT * FROM books postgres"# WHERE subject_id = i LOOP postgres"# postgres"# text_output := text_output || row_data.title || """"; postgres"# postgres"# END LOOP; postgres"# END LOOP; postgres"# RETURN text_output; postgres"# END; postgres"# " LANGUAGE "plpgsql"; CREATE FUNCTION postgres=# postgres=# select extract_all_titles2();
extract_all_titles2
Arts:CBusiness:Children:OracleSql ServerPostgre SQLPythonClassics:2DComputers:Programming PythonLearning PythonPerl CookbookPractical PostgreSQLCooking:Drama:Java by APIEntertainment:History:Horror:JavaC++Mystery:Poetry:Religion:Romance:Science:Science Fiction:JavascriptC#
(1 row) postgres=# postgres=# postgres=# drop table books; DROP TABLE postgres=# drop table subjects; DROP TABLE postgres=#
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