Oracle Column table Count - Sub-Selection-CodePudding

I really only want the number of columns in the tables in the SQL query, but somehow i can't get the right result. Does anybody know what I'm doing wrong?

select count(*) from user_tab_columns where table_name='tablename' //works and gives me the number of columns


select 
    TABLE_NAME, 
    NUM_ROWS,
    (select count(*) from user_tab_columns where table_name=TABLE_NAME) as Test
from user_tables

CodePudding user response：

Haha, look at this:

where table_name=TABLE_NAME

This will always be true, because the table name is the table name.

Here is the query with qualified column names:

select 
  table_name, 
  num_rows,
  (select count(*) from user_tab_columns tc where tc.table_name = t.table_name) as test
from user_tables t;