While Loop to Iterate through Databases - sql

Question

I was wondering if someone could help me with creating a while loop to iterate through several databases to obtain data from one table from two columns. this is was I have done so far. nothing works because i do not know how to make the select statement work through each database with regards to the table that I am querying from each database (dbo.tbldoc)
DECLARE #Loop int
DECLARE #DBName varchar(300)
DECLARE #SQL varchar(max)
DECLARE #tableName VARCHAR(255)
SET #Loop = 1
SET #DBName = ''
WHILE #Loop = 1
BEGIN
SELECT [name] FROM sys.databases
WHERE [name] like 'z%' and create_date between '2010-10-17' and '2011-01-15'
ORDER BY [name]
SET #Loop = ##ROWCOUNT
IF #Loop = 0
BREAK
SET #SQL = ('USE ['+ #DBNAME +']')
IF EXISTS(SELECT [name] FROM sys.tables WHERE name != 'dbo.tbldoc' )
BEGIN
SELECT SUM(PGCOUNT), CREATED FROM **dbo.tbldoc**
END
ELSE
--BEGIN
PRINT 'ErrorLog'
END

Answer 1

I would consider sp_MSForEachDB which is a lot easier...
Edit:
EXEC sp_MSForEachDB 'USE [?]; IF DB_NAME() LIKE ''Z%%''
BEGIN
END
'

Answer 2

CREATE TABLE #T
(dbname sysname NOT NULL PRIMARY KEY,
SumPGCOUNT INT,
CREATED DATETIME)
DECLARE #Script NVARCHAR(MAX) = ''
SELECT #Script = #Script + '
USE ' + QUOTENAME(name) + '
IF EXISTS(SELECT * FROM sys.tables WHERE OBJECT_ID=OBJECT_ID(''dbo.tbldoc''))
INSERT INTO #T
SELECT db_name() AS dbname, SUM(PGCOUNT) AS SumPGCOUNT, CREATED
FROM dbo.tbldoc
GROUP BY CREATED;
'
FROM sys.databases
WHERE state=0 AND user_access=0 and has_dbaccess(name) = 1
AND [name] like 'z%' and create_date between '2010-10-17' and '2011-01-15'
ORDER BY [name]
IF (##ROWCOUNT > 0)
BEGIN
--PRINT #Script
EXEC (#Script)
SELECT * FROM #T
END
DROP TABLE #T

Answer 3

My code to search for data from more than one database would be:
use [master]
go
if object_id('tempdb.dbo.#database') is not null
drop TABLE #database
go
create TABLE #database(id INT identity primary key, name sysname)
go
set nocount on
insert into #database(name)
select name
from sys.databases
where name like '%tgsdb%' --CHANGE HERE THE FILTERING RULE FOR YOUR DATABASES!
and source_database_id is null
order by name
Select *
from #database
declare #id INT, #cnt INT, #sql NVARCHAR(max), #currentDb sysname;
select #id = 1, #cnt = max(id)
from #database
while #id <= #cnt
BEGIN
select #currentDb = name
from #database
where id = #id
set #sql = 'select Column1, Column2 from ' + #currentDb + '.dbo.Table1'
print #sql
exec (#sql);
print '--------------------------------------------------------------------------'
set #id = #id + 1;
END
go

Answer 4

DECLARE #Loop int
DECLARE #MaxLoop int
DECLARE #DBName varchar(300)
DECLARE #SQL varchar(max)
SET #Loop = 1
SET #DBName = ''
set nocount on
SET #MaxLoop = (select count([name]) FROM sys.databases where [name] like 'Z%')
WHILE #Loop <= #MaxLoop
BEGIN
SET #DBName = (select TableWithRowsNumbers.name from (select ROW_NUMBER() OVER (ORDER by [name]) as Row,[name] FROM sys.databases where [name] like 'Z%' ) TableWithRowsNumbers where Row = #Loop)
SET #SQL = 'USE [' + #DBName + ']'
exec (#SQL)
...
...
set #Loop = #Loop + 1
END
***Note: I didn't add the check if exists here.

Answer 5

I ended up writing one last week on the fly for some stuff I was doing.
Blog post here:
http://tsells.wordpress.com/2012/02/14/sql-server-database-iterator/
Here is the code.
SET NOCOUNT ON
GO
use master
go
Declare
#dbname nvarchar(500),
#variable1 int,
#variable2 int,
#variable3 int,
#totaldb int = 0,
#totaldbonserver int = 0,
#totaldbwithmatches int = 0
-- Get non system databases
Declare mycursor CURSOR for select name, database_id from SYS.databases where database_id > 4 order by name desc
open mycursor
fetch next from mycursor into #dbname, #variable1
while (##FETCH_STATUS <> -1)
BEGIN
DECLARE #ParmDefinition NVARCHAR(500)
Declare #mysql nvarchar(500) = 'select #variable2OUT = COUNT(*) from [' + #dbname + '].INFORMATION_SCHEMA.TABLES where Upper(TABLE_NAME) like ''MyTable''';
SET #ParmDefinition = N'#variable2OUT int OUTPUT'
set #totaldbonserver = #totaldbonserver + 1
Execute sp_executesql #mysql, #ParmDefinition, #variable2 OUTPUT
if #variable2 = 1
BEGIN
DECLARE #ParmDefinition2 NVARCHAR(500)
Declare #mysql2 nvarchar(500) = 'select #variable2OUT = COUNT(*) from [' + #dbname + '].dbo.MyTable';
SET #ParmDefinition2 = N'#variable2OUT int OUTPUT'
Execute sp_executesql #mysql2, #ParmDefinition2, #variable3 OUTPUT
set #totaldb = #totaldb + 1
if #variable3 > 1
BEGIN
Print #dbname + ' matched the criteria'
set #totaldbwithmatches = #totaldbwithmatches + 1
END
ELSE
Select 1
END
fetch next from mycursor into #dbname, #variable1
END
PRINT 'Total databases on server: '
Print #totaldbonserver
PRINT 'Total databases tested () : '
Print #totaldb
PRINT 'Total databases with matches: '
Print #totaldbwithmatches
CLOSE mycursor
DEALLOCATE mycursor

Answer 6

This doesn't use a loop. Hope this helps!
Note that "TABLE_OWNER" is that same as "SCHEMA Owner" and "TABLE_TYPE" will identify if the item is a table OR view.
--This will return all tables, table owners and table types for all database(s) that are NOT 'Offline'
--Offline database information will not appear
Declare #temp_table table(
DB_NAME varchar(max),
TABLE_OWNER varchar(max),
TABLE_NAME varchar(max),
TABLE_TYPE varchar(max),
REMARKS varchar(max)
)
INSERT INTO #temp_table (DB_NAME, TABLE_OWNER, TABLE_NAME, TABLE_TYPE,REMARKS)
EXECUTE master.sys.sp_MSforeachdb 'USE [?]; EXEC sp_tables'
SELECT DB_NAME, TABLE_OWNER, TABLE_NAME, TABLE_TYPE
FROM #temp_table
--Uncomment below if you are seaching for 1 database
--WHERE DB_NAME = '<Enter specific DB Name>'
--For all databases other than 'System Databases'
WHERE DB_NAME not in ('master','model','msdn','tempdb')
order by 1,2,3

Answer 7

You don't have to use a "USE DATABASE" statement. You can select from the particular database table by using a 3 part identifier as in:
select * from MyDatabase.dbo.MyTable