How to check if a database exists in SQL Server?

Question

What is the ideal way to check if a database exists on a SQL Server using TSQL? It seems multiple approaches to implement this.

Answer 1

From a Microsoft's script:

DECLARE @dbname nvarchar(128)
SET @dbname = N'Senna'

IF (EXISTS (SELECT name 
FROM master.dbo.sysdatabases 
WHERE ('[' + name + ']' = @dbname 
OR name = @dbname)))

-- code mine :)
PRINT 'db exists'

Answer 2

IF EXISTS (SELECT name FROM master.sys.databases WHERE name = N'YourDatabaseName')
  Do your thing...

By the way, this came directly from SQL Server Studio, so if you have access to this tool, I recommend you start playing with the various "Script xxxx AS" functions that are available. Will make your life easier! :)

Answer 3

TRY THIS

IF EXISTS 
   (
     SELECT name FROM master.dbo.sysdatabases 
    WHERE name = N'New_Database'
    )
BEGIN
    SELECT 'Database Name already Exist' AS Message
END
ELSE
BEGIN
    CREATE DATABASE [New_Database]
    SELECT 'New Database is Created'
END

Answer 4

I like @Eduardo's answer and I liked the accepted answer. I like to get back a boolean from something like this, so I wrote it up for you guys.

CREATE FUNCTION dbo.DatabaseExists(@dbname nvarchar(128))
RETURNS bit
AS
BEGIN
    declare @result bit = 0 
    SELECT @result = CAST(
        CASE WHEN db_id(@dbname) is not null THEN 1 
        ELSE 0 
        END 
    AS BIT)
    return @result
END
GO

Now you can use it like this:

select [dbo].[DatabaseExists]('master') --returns 1
select [dbo].[DatabaseExists]('slave') --returns 0

Answer 5

Actually it's best to use:

IF DB_ID('dms') IS NOT NULL
   --code mine :)
   print 'db exists'

See https://docs.microsoft.com/en-us/sql/t-sql/functions/db-id-transact-sql