Query All Databases Listed In Table

Question

I have been using a cursor to get my results, but it is taking an extended period of time to return my result set. I am hoping to find a way to QUICKLY get the results returned (if at all possible). Here is my data structure with garbage DDL.

1st problem is each employee has there own table. I understand this is a major design flaw, and we are quickly working to remedy this, but I need an alternative until all elements have been updated. All 3 tables geoffrey, jorge, mitch all have the same structure, and I have attached sample DDL for geoffrey, & jorge and below is a sample query that shows what I need to query from each of the two tables.

Greatly appreciate any and all help on how to achieve this result!

Create Table #ReviewDB
(
  [TableName] varchar(500)
  ,[ServerDBTable] varchar(MAX)
)
Insert Into #ReviewDB VALUES
('geoffrey', 'beans.franks.dbo.geoffrey')
,('jorge', 'smallpox.virus.dbo.jorge')
,('mitch', 'mosquito.insect.dbo.mitch')
Create Table #geoffrey
(
  recordID int IDENTITY(1,1) PRIMARY KEY
  ,firstname varchar(500)
  ,lastname varchar(500)
  ,address varchar(500)
  ,city varchar(500)
  ,state varchar(500)
  ,zip varchar(500)
  ,phone varchar(500)
  ,itemsold varchar(500)
  ,saledate datetime
  ,managerapproved varchar(500)
)
Insert Into #geoffrey VALUES
('manny', 'ramirez', '1111111 aoaswdfrljkasdf ', 'topaz', 'mn', '1111', '9995552222', 'sofa', '01/21/2016', '')
,('hi', 'ho', '2323 aoaswdfrljkasdf ', 'topaz', 'mn', '1111', '6662229888', 'chair', '02/21/2016', '')
,('ee', 'aa', '4646 aoaswdfrljkasdf ', 'topaz', 'mn', '1111', '3332221919', 'ottoman', '01/21/2016', '')
Create Table #jorge
(
  recordID int IDENTITY(1,1) PRIMARY KEY
  ,firstname varchar(500)
  ,lastname varchar(500)
  ,address varchar(500)
  ,city varchar(500)
  ,state varchar(500)
  ,zip varchar(500)
  ,phone varchar(500)
  ,itemsold varchar(500)
  ,saledate datetime
  ,managerapproved varchar(500)
)
Insert Into #jorge VALUES
('aa', 'bb', '1111111 c street ', 'holt', 'tn', '2222', '1113334444', 'sofa', '01/21/2016', '')
,('cc', 'ddo', '2323 b street ', 'holt', 'tn', '2222', '8889997788', 'chair', '02/21/2016', '')
,('mm', 'rr', '4646 e street ', 'holt', 'tn', '2222', '8889998877', 'ottoman', '03/21/2016', '')
Create Table #managerrevieweddata
(
  ID int IDENTITY(1,1) PRIMARY KEY
  ,recordID int
  ,dbname varchar(500)
  ,managernotes text
  ,regionalmanager varchar(500)
  ,districtmanager varchar(500)
  ,incentiveitem varchar(500)
)
Insert Into #managerrevieweddata VALUES
('1', 'geoffrey', 'Valid sale, remind to offer upsell next time.', 'Regional Manager', 'District Manager', 'No')
,('2', 'jorge', 'Review with salesman', 'Regional Manager', 'District Manager', 'NO')

And here is a query that shows what I want my desired output to be.

I need a way to query each serverdbtable in #ReviewDB and return the below select statement

Declare @saledate datetime
Set @saledate = '03/21/2016'

Select a.firstname, a.lastname, a.address, a.city, 
a.state, a.zip, a.phone,   a.itemsold, a.saledate,
b.dbname, b.managernotes, b.regionalmanager, 
b.districtmanager, b.incentiveitem
FROM #ReviewDB.ServerDBTable a
INNER JOIN #managerrevieweddata b
ON a.recordID = b.recordID
and a.saledate = @saledate

Answer 1

It is unlikely that the cursor you are using is the cause of the delay in returning results. Most likely, the delay is due to running many select statements over possibly a large amount of data. Having said that, I likely wouldn't use the DECLARE CURSOR cur FOR ... construct to solve this issue.

I generally approach this class of problem by generating a single dynamic SQL statement, then execute that statement using either sp_executesql() or EXEC (), as in:

IF COALESCE(OBJECT_ID('dbo.TableList'), 0) <> 0
DROP TABLE dbo.TableList;

CREATE TABLE dbo.TableList
(
    DatabaseName SYSNAME NOT NULL
    , SchemaName SYSNAME NOT NULL
    , TableName SYSNAME NOT NULL
);

INSERT INTO dbo.TableList(DatabaseName, SchemaName, TableName)
VALUES ('Database1', 'Schema1', 'Table1')
    ,  ('Database2', 'Schema2', 'Table2');

DECLARE @cmd NVARCHAR(MAX);
SET @cmd = '';

SELECT @cmd = @cmd + CASE WHEN @cmd = '' THEN '' ELSE CHAR(13) + CHAR(10) END 
    + 'SELECT ''' + tl.DatabaseName 
        + '.' + tl.SchemaName 
        + '.' + tl.TableName 
        + ''', * '
    + 'FROM ' + QUOTENAME(tl.DatabaseName) 
        + '.' + QUOTENAME(tl.SchemaName) 
        + '.' + QUOTENAME(tl.TableName) + ';'
FROM dbo.TableList tl;

PRINT (@cmd);
EXEC sp_executesql @cmd;

This constructs statements required from the TableList table, appending each statement into a variable. The variable contents are then executed using the sp_executesql system stored procedure. This methodology can be used for a multitude of problems where you need to generate T-SQL statements based on the results of some query.

The output will be a single result set for each row in TableList - you probably don't want to do this for more than about 50 or 100 tables since the output might become unmanageable. If you have a lot of tables, you may want to consider inserting the output into a temporary table, then running a single select statement against that table.

If the structure of the tables listed in the TableName column are identical, you can use a UNION ALL to join the output into a single resultset:

SELECT @cmd = @cmd + CASE WHEN @cmd = '' THEN '' ELSE CHAR(13) + CHAR(10) 
    + 'UNION ALL' + CHAR(13) + CHAR(10) END 
    + 'SELECT ''' + tl.DatabaseName 
        + '.' + tl.SchemaName 
        + '.' + tl.TableName 
        + ''', * '
    + 'FROM ' + QUOTENAME(tl.DatabaseName) 
        + '.' + QUOTENAME(tl.SchemaName) 
        + '.' + QUOTENAME(tl.TableName) + ';'
FROM dbo.TableList tl;

Be aware that UNION ALL is generally much faster than UNION since the ALL option doesn't need to run a DISTINCT operator over the data.