mysql query returning double rows -

i using standard apache2 lamp configuration (mysql , php5), , utf8 encoding.

i have set 4 tables.

the first 1 named articles , has 6 columns:

id int(11) auto_increment primary key, title varchar(1000), posted (timestamp) author_id int(11), extract text, body text 

the second 1 named authors

id int(11) auto increment primary key, name varchar(100), img varchar(100), bio text 

the third 1 named categories

id int(2) auto_increment primary key, cat_name varchar(100) 

and fourth 1 named article_categories

id int(2) auto_increment primary key, article_id int(11), category_id int(2) 

now want write mysql query find title, author name , cat_name of article. far i've come this, , returns 10 rows, categories i've set up. (i've set 1 article 2 categories, , 5 categories in categories table).

this query:

select articles.title, authors.name, categories.cat_name articles, authors, categories, article_categories  title '%introduction%'; 

and result:

+------------------------+-----------------------+--------------+ | title                  | name                  | cat_name     | +------------------------+-----------------------+--------------+ | introduction ptc | yannick Šušteršič     | free         | | introduction ptc | yannick Šušteršič     | free         | | introduction ptc | yannick Šušteršič     | members-only | | introduction ptc | yannick Šušteršič     | members-only | | introduction ptc | yannick Šušteršič     | milestone    | | introduction ptc | yannick Šušteršič     | milestone    | | introduction ptc | yannick Šušteršič     | basic        | | introduction ptc | yannick Šušteršič     | basic        | | introduction ptc | yannick Šušteršič     | advanced     | | introduction ptc | yannick Šušteršič     | advanced     | +------------------------+-----------------------+--------------+ 

is there way display article once, corresponding categories name in single row?

if not, how relevant results? doing wrong? thanks

you forget compare author , articles vs categories :

select     articles.title, authors.name, group_concat(categories.cat_name)              articles, authors, categories, article_categories      title '%introduction%'     , articles.author_id = authors.id     , articles.id = article_categories.article_id     , article_categories.category_id = categories.id;  

updated, final correct statement, authored op.