Get the sizes of the largest and smallest tables in a database

AlanJ :

I'm a beginner in SQL and I've been given this command which returns the size of all tables in a given database.

SELECT 
    table_schema AS 'Database',
    table_name AS 'Table',
    ROUND(((data_length + index_length) / 1024 / 1024), 2) 'Size (MB)'
FROM
    information_schema.TABLES
WHERE
    table_schema = DATABASE-NAME
ORDER BY (data_length + index_length) DESC;

However, I'm trying to modify it so that the size of the largest and smallest tables in MB are returned.

In my last attempt to get the largest size I have tried this:

SELECT 
    table_schema AS 'Database', table_name AS 'Table', MAX(Size)
FROM
    (SELECT 
        (ROUND(((data_length + index_length) / 1024 / 1024), 2)) AS Size
    FROM
        information_schema.TABLES) AS subquery
WHERE
    table_schema = DATABASE-NAME;

But I got an error (error code 1054) saying that 'table_schema' in 'field list' does not exist.

I know how to use aggregate functions to get the min and max values from a regular column, but I don't see how to do it with an alias column.

Sebastian Brosch :

You can use the following:

SELECT tInfo.table_schema, tInfo.table_name, ROUND(((tInfo.data_length + tInfo.index_length) / 1024 / 1024), 2) AS `Size (MB)` 
FROM information_schema.TABLES tInfo INNER JOIN (
    SELECT 
        table_schema,
        MAX(data_length + index_length) AS `max_size`,
        MIN(data_length + index_length) AS `min_size`
    FROM information_schema.TABLES
    GROUP BY table_schema
) tSizes ON tInfo.table_schema = tSizes.table_schema AND (tInfo.data_length + tInfo.index_length) IN (tSizes.`max_size`, tSizes.`min_size`)
WHERE tInfo.table_schema LIKE 'DATABASE-NAME'