Sql count group by

Problem

You’d like to determine how many rows a table has.

Example

Our database has a table named with data in the following columns: , (electronic identifier), and .

id	eID	name
1	23456	sparky
2	23457	mily
3	NULL	lessy
4	NULL	carl
5	34545	maggy

Let’s count all rows in the table.

Solution

counts the total number of rows in the table:

SELECT COUNT(*) as count_pet FROM pet;

Here’s the result:

Instead of passing in the asterisk as the argument, you can use the name of a specific column:

SELECT COUNT(id) as count_pet FROM pet;

In this case, counts the number of rows in which is not .

Discussion

Use the aggregate function to count the number of rows in a table. This function takes the name of the column as its argument (e.g., ) and returns the number of rows for this particular column in the table (e.g., 5).

As mentioned above, when you specify a column instead of the asterisk, the function will only count non- values.

Since id is the primary key of our table—and therefore has unique and non- values—it’s a good candidate for counting

how to get row number in sql

how to get row number in sqlite