In this part, we will analyze the system’s performance using SQL queries. Use of Amazon Athena will be charged when you query, based on the amount of scanned data ( scan ) which is monthly recorded data and the file is in parquet format. This data has been compressed and fragmented to reduce costs when using Amazon Athena. However, the query should still limit the number of records returned with the limit keyword at the end of the statement.
SQL SELECT statement: SELECT is used to select data from the database. The returned data is stored in a result table.
SQL SELECT DISTINCT statement: SELECT DISTINCT is used to return distinct (different) values. Inside a table, a column often contains many duplicate values; and sometimes you just want to list different (separate) values.
WHERE clause in SQL: WHERE clause is used to filter records. It is only used to extract those records that meet a specific condition.
SQL statement GROUP BY: GROUP BY is used to group rows with the same value into summary rows.
SQL statement ORDER BY: ORDER BY is used to sort the result set in ascending or descending order.
SQL LIKE operator: The LIKE operator is used in a WHERE clause to search for a specific pattern in a column.
LIMIT keyword: limit the number of records returned