What is the difference between SELECT COUNT(*) and SELECT COUNT(column) FROM table?

The difference between SELECT COUNT(*) and SELECT COUNT(column) in SQL is in which rows are counted:

• SELECT COUNT(*) FROM table — counts all rows in the table, including those where column values may be NULL.

• SELECT COUNT(column) FROM table — counts only the rows where the value in the specified column is not NULL.

Example:

id	name
1	Alice
2	NULL
3	Bob

• SELECT COUNT(*) FROM table will return 3.
• SELECT COUNT(name) FROM table will return 2, as one record contains NULL in the name column.

Thus, COUNT(column) is useful when you want to count only non-empty values in a specific column.