Two of the metadata functions available in SQL Server include DB_NAME() and ORIGINAL_DB_NAME(). Both functions are similar in that they return the name of a database. But they are also different. You definitely don’t want to confuse the two, as they serve different purposes.

In a nutshell, each function works as follows:

• DB_NAME() returns the name of a specified database. If you don’t explicitly specify a database, it returns the current database.
• ORIGINAL_DB_NAME() returns the database name specified by the user in the database connection string.

Example 1 – Initial Connection

Consider the following connection string:

mssql-cli -S localhost -U sa -P bigStrongPassword!!! -d WideWorldImporters

This is the connection string I provided when using the mssql-cli command line tool to connect to SQL Server.

This connection string includes -d WideWorldImporters, which means that the WideWorldImporters database will be the initial database. Once I get connected to SQL Server, my current database will be WideWorldImporters.

Here’s what I get when I run both functions after logging in with the above connection string:

SELECT 
  DB_NAME() AS [Current Database],
  ORIGINAL_DB_NAME() AS [Original Database],
  DB_NAME(5) AS [Another Database];

Result:

+--------------------+---------------------+--------------------+
| Current Database   | Original Database   | Another Database   |
|--------------------+---------------------+--------------------|
| WideWorldImporters | WideWorldImporters  | MyDB               |
+--------------------+---------------------+--------------------+

Example 2 – Switch Databases

Here’s what happens if I switch to a different database and run the statement again:

USE Music;
SELECT 
  DB_NAME() AS [Current Database],
  ORIGINAL_DB_NAME() AS [Original Database],
  DB_NAME(5) AS [Another Database];

Result:

+--------------------+---------------------+--------------------+
| Current Database   | Original Database   | Another Database   |
|--------------------+---------------------+--------------------|
| Music              | WideWorldImporters  | MyDB               |
+--------------------+---------------------+--------------------+

The current database changes, but original database remains the same. The third column also remains the same because I specified the same database ID (5) when calling DB_NAME().

Example 3 – Default Database

Here’s what happens if I don’t explicitly specify a database in the connection string:

mssql-cli -S localhost -U sa -P bigStrongPassword!!!

Now run ORIGINAL_DB_NAME():

SELECT 
  DB_NAME() AS [Current Database],
  ORIGINAL_DB_NAME() AS [Original Database],
  DB_NAME(5) AS [Another Database];

Result:

+--------------------+---------------------+--------------------+
| Current Database   | Original Database   | Another Database   |
|--------------------+---------------------+--------------------|
| master             | master              | MyDB               |
+--------------------+---------------------+--------------------+

The default database for that user is used, which in this case is the master database.