Difference between count (*) and count (field name) in SQL

Source: Internet
Author: User

Difference between count (*) and count (field name) in SQL
This article uses examples to describe the differences between count (*) and count (field name) in SQL. For details, refer to examples.

I did not pay attention to the difference between the two in the past. Reading the blog garden articles really caught my attention.

Data Testing: see Figure

SQL statements:

Select count (*) c1, COUNT (ADDRESS) c2 FROM test

Obviously, count (*) counts the total number of results set, and count (field name) counts the total number of records where the field value is not null.

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