A better sp_MSForEachDB

Though undocumented and unsupported, I’m sure that at least once you happened to use Microsoft’s built-in stored procedure to execute a statement against all databases. Let’s face it: it comes handy very often, especially for maintenance tasks.

Some months ago, Aaron Bertand (blog|twitter) came up with a nice replacement and I thought it would be fun to code my own.

The main difference with his (and Microsoft’s) implementation is the absence of a cursor. While flagged correctly (LOCAL FORWARD_ONLY STATIC READ_ONLY) and run against a temporary table, nevertheless I was a bit disturbed by that tiny little cursor, so I decided to get rid of it.

Basically, my code relies on a dynamic SQL pushed down three levels:

1. sp_executesql
2. sp_executesql
3. EXEC

This trick can be used as many times as you like, given that you keep on declaring and passing all the parameters you need to the lower levels.

I didn’t provide ad-hoc parameters to implement complex filters on sysdatabases, as I’m convinced that they would not be useful enough in a day to day use. If you like this code and want to use it, feel free to change it to incorporate any kind of filter.

Here is the code:

--
-- Author: Gianluca Sartori @spaghettidba
-- Date:   2011/09/09
--
-- Description: Executes a statement against multiple databases
-- Parameters:
--    @statement:    The statement to execute
--    @replacechar:  The character to replace with the database name
--    @name_pattern: The pattern to select the databases
--                   It can be:
--                   * NULL     - Returns all databases
--                   * [USER]   - Returns users databases only
--                   * [SYSTEM] - Returns system databases only
--                   * A pattern to use in a LIKE predicate against the database name
CREATE PROCEDURE [dba_ForEachDB]
    @statement    nvarchar(max),
    @replacechar  nchar(1)      = N'?',
    @name_pattern nvarchar(500) = NULL
AS
BEGIN

    SET NOCOUNT ON

    DECLARE @sql nvarchar(max)

    -- LEVEL 3:
    -- Build an intermediate statement that replaces the '?' char
    SET @sql = 'SET @statement = REPLACE(@statement,'''+ @replacechar +''',DB_NAME()); EXEC(@statement);'
    SET @sql = REPLACE(@sql, '''', '''''')
    SET @sql = 'N''' + @sql + ''''

    -- LEVEL 2:
    -- Build a statement to execute on each database context
    ;WITH dbs AS (
        SELECT *,
            system_db = CASE WHEN name IN ('master','model','msdb','tempdb') THEN 1 ELSE 0 END
        FROM sys.databases
        WHERE   DATABASEPROPERTY(name, 'IsSingleUser') = 0
            AND HAS_DBACCESS(name) = 1
            AND state_desc = 'ONLINE'
    )
    SELECT @sql = (
        SELECT
            'EXEC ' + QUOTENAME(name) + '.sys.sp_executesql ' +
                @sql + ',' +
                'N''@statement nvarchar(max)'',' +
                '@statement;' AS [text()]
        FROM dbs
        WHERE 1 =
                CASE
                    -- No filter? Return all databases
                    WHEN @name_pattern IS NULL      THEN 1
                    -- User databases
                    WHEN @name_pattern = '[USER]'   THEN system_db + 1
                    -- System databases
                    WHEN @name_pattern = '[SYSTEM]' THEN system_db
                    -- LIKE filter
                    WHEN name LIKE @name_pattern    THEN 1
                END
        ORDER BY name
        FOR XML PATH('')
    )

    -- LEVEL 1:
    -- Execute multi-db sql and pass in the actual statement
    EXEC sp_executeSQL @sql, N'@statement nvarchar(max)', @statement

END

Let’s see some examples of its use:
Print the database name for each user database:

EXEC [dba_ForEachDB] @statement = 'PRINT DB_NAME()', @replacechar = '?', @name_pattern =  '[USER]'

Display the file path of each database file of system databases:

EXEC [dba_ForEachDB] @statement = 'SELECT physical_name, size FROM sys.database_files', @replacechar = '?', @name_pattern =  '[SYSTEM]'

I hope you like it and find it useful.
Happy coding.