Count All Three Salary Categories Including Empty Ones

### Problem Return category and accounts_count for all three source categories: Low Salary for income < 20000, Average Salary for 20000 through 50000 inclusive, and High Salary for income > 50000. Always emit the three categories, with 0 for an empty category. Row ordering is unrestricted. ### Tables Table: `Accounts` ```text +-------------+------+ | Column Name | Type | +-------------+------+ | account_id | int | | income | int | +-------------+------+ account_id is the primary key (column with unique values) for this table. Each row contains information about the monthly income for one bank account. ``` ### Example ```text Accounts (account_id,income): (1,19999), (2,20000), (3,50000), (4,50001) Output (category,accounts_count): (Low Salary,1), (Average Salary,2), (High Salary,1) If Accounts is empty, every one of the same three categories has count 0. ``` ### What a Strong Answer Covers - Return exactly the three named categories and apply their specified boundaries. - Return zero for a category with no accounts. ### Follow-up Questions - How would the query change if salary categories were stored in a separate table? - How would you return the share of all accounts in each category?