To get e.g. the current wikitext of a given page in the main namespace:
INNER JOIN revision ON page_latest = rev_id
INNER JOIN text ON rev_text_id = old_id
page_title = 'Your page title'
Note: The use of LEFT(old_text,1024)
allows the first 1024 characters to be printed because, old_text being a blob, your query would probably only display "[BLOB - <n>.<n> KiB]" where <n>.<n> is the size in kilobytes of your page content. If you are using this query in a program and need the entire content in old_text, be sure to only reference old_text and not LEFT(old_text,1024).
a person who wants to convert blob to char(1000) with utf8 encoding
CAST(a.ar_options AS CHAR(10000) CHARACTER SET utf8)