Question

Is there a way to know the number of columns in SQL, something like count()…?

Answer 1

one way

select count(*) from sys.columns 

another

select count(*) from information_schema.columns

The bottom one does not have the system tables

by table

select count(*),table_name from information_schema.COLUMNS
GROUP BY table_name

tables only

select count(*),c.table_name 
from information_schema.COLUMNS c
JOIN information_schema.tables t ON c.TABLE_NAME = t.TABLE_NAME
AND c.TABLE_Schema = t.TABLE_Schema
WHERE TABLE_TYPE = 'base table'  
GROUP BY c.table_name

views only

select count(*),c.table_name 
from information_schema.COLUMNS c
JOIN information_schema.tables t ON c.TABLE_NAME = t.TABLE_NAME
AND c.TABLE_Schema = t.TABLE_Schema
WHERE TABLE_TYPE = 'view'  
GROUP BY c.table_name