sql count

/*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(*)
FROM information_schema.columns
WHERE table_name = 'Your_table_nale';

SELECT COUNT(*)
FROM dbo.bigTransactionHistory;

SELECT COUNT(column_name)

FROM table_name

WHERE condition; 

SELECT SUM(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;

SELECT AVG(column_name)

FROM table_name

WHERE condition;