What is SQLite COUNT aggregate function?

SQLite's COUNT aggregate function is used to count the number of rows in a table, regardless of the values in those rows. In simple terms, it helps us determine how many rows are present in the table.

Usage Scenarios:

1. Count Total Rows: When determining the total number of records in a table, we can use COUNT(*). The * symbol denotes all rows in the table.

   Example:

   sql
   SELECT COUNT(*) FROM employees;

   This statement returns the total number of rows in the employees table.

2. Count Non-Null Values in a Specific Column: If we are interested in counting non-null values in a specific column, we can use COUNT(column_name).

   Example:

   sql
   SELECT COUNT(last_name) FROM employees;

   This returns the number of non-null values in the last_name column.

3. Conditional Counting: Using the WHERE clause, we can count rows that satisfy specific conditions.

   Example:

   sql
   SELECT COUNT(*) FROM employees WHERE department = 'Sales';

   This returns the count of employees in the Sales department.

In summary, the COUNT aggregate function is a powerful tool that helps us quickly obtain key information during data analysis and report generation.