diff --git a/sql-queries-12/database-size/mssql.sql b/sql-queries-12/database-size/mssql.sql
new file mode 100644
index 00000000..0a159211
--- /dev/null
+++ b/sql-queries-12/database-size/mssql.sql
@@ -0,0 +1,13 @@
+EXEC sp_spaceused;
+
+SELECT DB_NAME(database_id) AS [Database], CAST(SUM(size) * 8 / 1024 AS VARCHAR(20)) + ' MB' AS [Size] 
+  FROM sys.master_files 
+  WHERE DB_NAME(database_id) = 'university' 
+  GROUP BY database_id;
+
+SELECT d.name AS [Database], CAST(SUM(mf.size) * 8 / 1024 AS VARCHAR(20)) + ' MB' AS [Size] 
+  FROM sys.databases d 
+  JOIN sys.master_files mf 
+  ON d.database_id = mf.database_id 
+  GROUP BY d.name 
+  ORDER BY SUM(mf.size) DESC;
diff --git a/sql-queries-12/database-size/mysql.sql b/sql-queries-12/database-size/mysql.sql
new file mode 100644
index 00000000..19c8bcb1
--- /dev/null
+++ b/sql-queries-12/database-size/mysql.sql
@@ -0,0 +1,9 @@
+SELECT table_schema AS "Database", FLOOR(SUM(data_length + index_length) / 1024 / 1024, 2) AS "Size (MB)" 
+  FROM information_schema.tables 
+  WHERE table_schema = 'university' 
+  GROUP BY table_schema;
+
+SELECT table_schema AS "Database", FLOOR(SUM(data_length + index_length) / 1024 / 1024, 2) AS "Size (MB)" 
+  FROM information_schema.tables 
+  GROUP BY table_schema 
+  ORDER BY SUM(data_length + index_length) DESC;
diff --git a/sql-queries-12/database-size/postgresql.sql b/sql-queries-12/database-size/postgresql.sql
new file mode 100644
index 00000000..7deea05a
--- /dev/null
+++ b/sql-queries-12/database-size/postgresql.sql
@@ -0,0 +1,7 @@
+SELECT pg_database.datname AS "Database", size_pretty(pg_database_size(pg_database.datname)) AS "Size" 
+  FROM pg_database 
+  WHERE datname = 'university';
+
+SELECT datname AS "Database", pg_size_pretty(pg_database_size(datname)) AS "Size" 
+  FROM pg_database 
+  ORDER BY pg_database_size(datname) DESC;