SQL Server: How to Get a Database Name as a Parameter in a Stored Procedure

SQL Server: how to get a database name as a parameter in a stored procedure

EDIT

My answer assumes some things which make this approach effectively useless. Unfortunately, SO will not let me delete the answer. I recommend @MartinSmith's answer (below in this thread). I think there's still some useful information here, BUT it doesn't actually solve the original problem. Godspeed.

Original Response

There are at least two ways to do this:

1. Use a case/switch statement (or ,in my example, a naive if..else block) to compare the parameter against a list of databases, and execute a using statement based on that. This has the advantage of limiting the databases that the proc can access to a known set, rather than allowing access anything and everything that the user account has rights to.

    declare @dbname nvarchar(255);    
    set @dbname = 'db1';    
    if @dbname = 'db1'
     use db1;
    else if @dbname = 'db2'
     use db2;
   

2. Dynamic SQL. I HATE dynamic SQL. It's a huge security hole and almost never necessary. (to put this in perspective: In 17 years of professional development, I have never had to deploy a production system which used dynamic SQL). If you decide to go this route, limit the code that is dynamically called/created to a using statement, and a call to another stored proc do do the actual work. You can't just dynamically execute the using statement by itself due to scope rules.

    declare @sql nvarchar(255);
    set @sql = 'using '+@dbname+'; exec mydatabase..do_work_proc;';
   

of course, in your example, you could just do

    set @sql='select * from '+@dbname+'.sys.tables';

the .<schema_name>. resolution operator allows you to query objects in a different database without using a use statement.

There are some very, very rare circumstances in which it may be desirable to allow a sproc to use an arbitrary database. In my opinion, the only acceptable use is a code generator, or some sort of database analysis tool which cannot know the required information ahead of time.

Update Turns out you can't use in a stored procedure, leaving dynamic SQL as the only obvious method. Still, I'd consider using

select top 100 * from db_name.dbo.table_name

rather than a use.

SQL Server: How to use a database name as a parameter in a stored procedure?

You have to use dynamic sql:

@DBname = 'sample';
declare @sql nvarchar(max);

set @sql = '
SELECT *
FROM Table1 INNER JOIN
     @DBname.table2
     On Table1.key = Table2.Key';

set @sql = replace(@sql, '@DBname', @DBname);

exec sp_executesql @sql;

Databases in general -- and SQL Server in particular -- do not allow parameters to represent database names, schema names, table names, or column names.

Execute stored procedure with variable database name

So this version of your code shows includes debugging code. Remember that concatenating null values will result in a null value.

IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[DGP_addVendor]') AND type in (N'P', N'PC'))
    DROP PROCEDURE [DGP_addVendor]
GO

CREATE PROCEDURE [dbo].[DGP_addVendor]
    @dbName VARCHAR(4) = NULL ,
    @NoteIndex NUMERIC(19, 5) = NULL ,
    @VENDORID CHAR(15) = NULL ,
    @VENDNAME CHAR(65) = NULL ,
    @DEX_ROW_ID INT = NULL OUTPUT ,
    @O_ErrorCode INT = NULL OUTPUT ,
    @ADDRESS1 CHAR(61) = '' ,
    @ADDRESS2 CHAR(61) = '' ,
    @ADDRESS3 CHAR(61) = '' ,
    @CITY CHAR(35) = '' ,
    @STATE CHAR(29) = '' ,
    @ZIPCODE CHAR(11) = '' ,
    @COUNTRY CHAR(61) = '' ,
    @PHNUMBR1 CHAR(21) = ''
AS
    DECLARE @today DATETIME ,
        @defaultDate DATETIME ,
        @sql VARCHAR(MAX)

    IF @DEX_ROW_ID IS NULL
        SET @DEX_ROW_ID = -1
    SET @today = CONVERT(DATETIME, '01/01/1900')
    SET @defaultDate = CONVERT(DATETIME, '01/01/1900')

    SET @sql = 'EXEC ' + @dbName + '.dbo.zDP_PM00200SI
     ''' + @VENDORID + '''
    ,''' + @VENDNAME + '''
    ,''' + @VENDNAME + '''
    ,''' + @VENDNAME + '''
    ,''PRIMARY''
    ,''PRIMARY''
    ,''PRIMARY''
    ,''PRIMARY''
    ,''''
    ,''''
    ,''' + @ADDRESS1 + '''
    ,''' + @ADDRESS2 + '''
    ,''' + @ADDRESS3 + '''
    ,''' + @CITY + '''
    ,''' + @STATE + '''
    ,''' + @ZIPCODE + '''
    ,''' + @COUNTRY + '''
    ,''' + @PHNUMBR1 + '''
    ,''''
    ,''''
    ,''''
    ,''''
    ,''''
    ,''''
    ,''''
    ,''''
    ,1
    ,''''
    ,''''
    ,''''
    ,0
    ,1
    ,0
    ,0
    ,''''
    ,0
    ,0
    ,0
    ,0
    ,0
    ,''''
    ,''''
    ,''''
    ,''''
    ,0
    ,''''
    ,1
    ,1
    ,1
    ,1
    ,0
    ,0
    ,1
    ,1
    ,0
    ,0
    ,0
    ,''''
    ,' + CONVERT(VARCHAR, @defaultDate) + '
    ,' + CONVERT(VARCHAR, @defaultDate) + '
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,' + CONVERT(VARCHAR, @NoteIndex) + '
    ,''''
    ,' + CONVERT(VARCHAR, @today) + '
    ,' + CONVERT(VARCHAR, @today) + '
    ,''''
    ,1
    ,0
    ,1
    ,''''
    ,''''
    ,0
    ,0
    ,''''
    ,0
    ,0
    ,0
    ,0
    ,0
    ,0
    ,' + CONVERT(VARCHAR, @defaultDate) + '
    ,0
    ,''''
    ,''''
    ,0
    ,9
    ,0
    ,''PRIMARY''
    ,' + CONVERT(VARCHAR, @DEX_ROW_ID) + ' OUT'

    SET @sql = '<?query -- ' + CHAR(13) + COALESCE(@sql,'') + + CHAR(13) + ' --?>'
    SELECT CONVERT(XML, @sql)

    --EXEC (@sql)  

    SELECT  @O_ErrorCode = @@ERROR

GO
DECLARE @index INT ,
    @row INT ,
    @error INT

SET @index = 1

EXEC [dbo].[DGP_addVendor] 'LFD', @index, 'ANT0000001',
    'Anthony Quisenberry', @row OUT, @error OUT, '8506 west Rd', '', '',
    'Louisville', 'KY', '40247', 'USA', ''

SELECT  @row AS [@row], @error AS [@error]

How can I get the database name from which stored procedure is called?

If I remember correctly, I don't think it is possible.

There is a work-around, you can add an extra input parameter in proc2 and pass the information to it.

How to parameterize database name in SQL Server

DECLARE @oltp VARCHAR(50)
SET @oltp = 'Employee';

DECLARE @wh VARCHAR(25)
SET @wh =  '_wh';

DECLARE @DatabaseName SYSNAME = @oltp + @wh;
   
IF NOT EXISTS ( SELECT 1 FROM sys.databases WHERE name = @DatabaseName)
    BEGIN
      DECLARE @ErrorMsg VARCHAR(1000);
      SET @ErrorMsg = QUOTENAME(@DatabaseName)  + ' database does not exist';
      RAISERROR(@ErrorMsg , 16 , 2); 
    END
ELSE 
BEGIN
    DECLARE @Sql NVARCHAR(MAX) = N'SELECT * FROM '  
                               + QUOTENAME(@DatabaseName) 
                               + N'..employee_sales_item;';

    EXEC sys.sp_executesql @Sql;
END

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