select count sql

/*COUNT(column_name) will return the number of rows from the column 
that are not NULL*/
SELECT COUNT(column_name)
FROM table_name;

/*COUNT(*) will return the number of rows from the table*/
SELECT COUNT(*)
FROM table_name;

SELECT COUNT(column_name)

FROM table_name

WHERE condition; 

/* COUNT() is a function that takes on the name of a clomn as an argument
and counts the number of rows where the column is not null */

SELECT COUNT(column_name)
FROM table_name;