The query returns basic statistics of the number of columns in a database (schema).

Query

select database_name,
    columns,
    tables, 
    cast((1.0*columns/tables) as decimal(10,2)) as average_column_count
from (
    select cols.table_schema as database_name,
        count(*) as 'columns',
        count(distinct cols.table_name) as 'tables'
    from information_schema.columns as cols
    inner join information_schema.tables as tabs
        on tabs.table_schema = cols.table_schema
        and tabs.table_name = cols.table_name
        and table_type = 'BASE TABLE'
        and tabs.table_schema not in ('mysql', 'sys', 'information_schema',
                             'performance_schema')
    group by database_name
) as q
order by columns desc;

Columns

• columns - total number of columns in a database (schema)
• tables - number of tables in a database (schema)
• average_column_count - average number of columns in a table in a database (schema)

Rows

• One row: represents a database (schema)
• Scope of rows: all databases (schemas)
• Ordered by: number of columns in descending order

Sample results