Question

Here are two cases I’ve run into recently:

1. Querying the set of tables for those that have more than 0 rows but less than 50 rows.
2. Querying all tables to find which has a column named a certain value.

Are either of these possible? If so, how?

Answer 1

To get a table with a specific column name:

select * from all_tab_columns where column_name = '<colname in upper case>';

An estimate of the number of rows in a table can be found:

select table_name, num_rows from all_tables where num_rows between 1 and 49;

This will be close if your statistics are up to date. If not, you need to create a pl/sql process to loop through the tables and perform a count(*) on them.

EDIT: Have found an Ask Tom article on the number of rows query: Finding the number of rows in each table by a single sql.