How to know the size of all tables in the database

The size of all tables in the database can be obtained by using a SQL query in the database management system, for example:

SQL:

SELECT 
    t.NAME AS TableName,
    s.Name AS SchemaName,
    p.rows,
    SUM(a.total_pages) * 8 AS TotalSpaceKB, 
    CAST(ROUND(((SUM(a.total_pages) * 8) / 1024.00), 2) AS NUMERIC(36, 2)) AS TotalSpaceMB,
    SUM(a.used_pages) * 8 AS UsedSpaceKB, 
    CAST(ROUND(((SUM(a.used_pages) * 8) / 1024.00), 2) AS NUMERIC(36, 2)) AS UsedSpaceMB, 
    (SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS UnusedSpaceKB,
    CAST(ROUND(((SUM(a.total_pages) - SUM(a.used_pages)) * 8) / 1024.00, 2) AS NUMERIC(36, 2)) AS UnusedSpaceMB
FROM 
    sys.tables t
INNER JOIN      
    sys.indexes i ON t.OBJECT_ID = i.object_id
INNER JOIN 
    sys.partitions p ON i.object_id = p.OBJECT_ID AND i.index_id = p.index_id
INNER JOIN 
    sys.allocation_units a ON p.partition_id = a.container_id
LEFT OUTER JOIN 
    sys.schemas s ON t.schema_id = s.schema_id
WHERE 
    t.NAME NOT LIKE 'dt%' 
    AND t.is_ms_shipped = 0
    AND i.OBJECT_ID > 255 
GROUP BY 
    t.Name, s.Name, p.Rows
ORDER BY 
    TotalSpaceMB DESC, t.Name

MYSQL:

SELECT 
  table_name AS "Table", 
  round(((data_length + index_length) / 1024 / 1024), 2) "Size (MB)"
FROM information_schema.TABLES 
WHERE table_schema = "database_name";

PostgreSQL:

SELECT 
  table_name, 
  pg_total_relation_size(table_name) / 1024 / 1024 as size_mb
FROM information_schema.tables 
WHERE table_schema = 'public';

Note: Replace “database_name” with the name of your database.

ORACLE:

SELECT table_name,
       round(sum(bytes) / (1024 * 1024), 2) "Size (MB)"
FROM   user_segments
GROUP BY table_name;

Note: The above query assumes that you are querying for tables in the user’s schema. If you want to query for tables in a different schema, replace “user_segments” with “all_segments” and “user_name” with the name of the desired schema.