I need to run a SELECT query on a SQL Server and return info pulled from multiple databases on the same server. I have the following, which could work:
SELECT [Name], [Nationality]
FROM [dbtest].[dbo].[Staff]
WHERE Nationality = 'Canadian'
Union all
SELECT [Name], [Nationality]
FROM [dbtest2].[dbo].[Staff]
WHERE Nationality = 'Canadian'
etc..
The problem is I have 2000 databases to query and it will almost certainly be added to in future, meaning the query will need editing.
What I really need is a wildcard for the database name.
ie:
*.[dbo].[Staff]
but this gives me an error. Even if it worked, not all databases have the same tables, so is likely to error anyway.
Any way I can do this without typing out the above example 2000 times ?
You can build the statement dynamically
DECLARE #Query varchar(max) = ''
SELECT #Query = COALESCE(#Query + ' UNION ALL ', '') + 'SELECT [Name], [Nationality] FROM [' + TABLE_CATALOG+'].dbo.[Staff] WHERE Nationality = ''Canadian'''
FROM information_schema.tables
WHERE table_name = 'Staff'
SET #Query = STUFF(#Query, CHARINDEX('UNION ALL', #Query), 10, '')
PRINT #Query
EXEC(#Query)
One way of doing that is to generate query on the fly.
Either by querying information_schema DMV as in #Yosi answer or by using your own metadata table (in case tables can have different names in different databases or there are any other significant differences in table's schema) :
Create some master database and create table here which will contain list of all other databases - mainly DB name but you can include any other information describing differences (and use this data during query generation). You can add more (or delete) database "definitions" here.
Create stored procedure which will iterate master table and generate query on the fly
Execute query using sp_exec
Related
I have been researching this for a couple of days and feel like I am going around in circles. I have basic knowledge of SQL but there are many areas I do not understand.
I have a table that stores the names and fields of all the other tables in my database.
tblFields
===================================================
TableName FieldName BookmarkName
---------------------------------------------------
Customer FirstName CustomerFirstName
Customer LastName CustomerLastName
Customer DOB CustomerDOB
I want to write a SELECT statement like the following but i am unable to get it work:
SELECT (SELECT [FieldName] FROM [TableName]) FROM tblFields
Is this possible? The application I have developed requires this for user customization of reports.
If i understand what you are trying to do, i think this will help you. It is not pretty and it works for SQL Server 2005 and above, but maybe this is what you are looking for:
declare #tableName nvarchar(100)
declare #sqlQuery nvarchar(max)
declare #fields varchar(500)
set #tableName = 'YourTableName'
set #fields = ''
select #fields = #fields + QUOTENAME(t.fieldname) + ',' from (
select distinct fieldname from tblfields where tablename = #tableName)t
set #sqlQuery = 'select ' + left(#fields, LEN(#fields)-1) + ' from ' + QUOTENAME(#tableName)
execute sp_executesql #sqlQuery
Edit: As Martin suggested, i edited so that the columns and tablename are using QUOTENAME
If I understand correctly what you are trying to do, you are probably better off doing this as two separate queries from your program. One which gets the fields you want to select which you then use in your program to build up the second query which actually gets the data.
If it must be done entirely in SQL, then you will need to tell us what database you are using. If it is SQL Server, you might be able to user a cursor over the first query to build up the second query which you then execute with the sp_executesql stored procedure. But doing doing it outside of SQL would be recommended.
I have many different application databases with a [Log] table. I have one central database with a similar log table, but with one extra column called TenantId. There is also a Tenant table with a TenantId and a DatabaseName column. These DatabaseName contain the names of the application databases.
Now I want to loop all the application databases and copy the log entries to the central log table, with the TenantId that belongs to the application database name.
Would it be possible to write one procedure in the central database instead of creating many procedures in the application databases? All databases are on the same SQL Server instance.
Just some quick Dynamic SQL. In the example below, CHINRUS is my central database and would therefore be excluded from consolidation.
I should add, that the WHERE should be tailored to exclude any misc database on the server. Yet another option would be to maintain a table which has the proper definitions.
Declare #LogTable varchar(100)='[Chinrus].[dbo].[TransactionLog]'
Declare #CentralDB varchar(100)='Chinrus'
Declare #SQL varchar(max) = ''
Select #SQL = #SQL + SQL
From (
Select Name,SQL=';Insert Into '+#LogTable+' Select *,TenantId='''+Name+''' From ['+Name+'].[dbo].[TransactionLog] '
From master.dbo.sysdatabases
Where Name<>#CentralDB
) A
Select #SQL
--Exec(#SQL)
You can get list of all databases with following query:
SELECT name
FROM master.dbo.sysdatabases
and then you can use a cursor to get each database data and insert in one table in current database.
SO,
I am trying to find a (messy?) solution to an even more messy problem. I have a SQL Server 2014 database which, in part, stores data from another software package but also stores data for me. The software creates a table with specific fields for each set of data - a Name and a Geometry field. For example, one might contain cities (dtCitiesData), another contains roads (dtRoadsData), another contains states(dtStates), etc. I also have a table (dtSpatialDataTables) which stores the names of the tables which store the data I want. That table only has 2 fields: ID and TableName.
I would like to create a SELECT statement which queries dtSpatialDataTables for all entries, then queries all tables with the name corresponding to each TableName result, and SELECTs Name and Geometry from them.
In pseudocode, effectively I want to do this:
SELECT TableName FROM dtSpatialDataTables
FOREACH TableName :
SELECT Name, Geometry FROM (TableName)
I can do this easily PHP via a first query against dtSpatialDataTables and then a loop of queries to each of the returned row TableNames but I want to know if this is possible via SQL directly.
In reality, what I want to do is create a VIEW with this query so I can directly query the VIEW rather than soak of processing time on potentially lots of queries.
Is this possible? Unfortunately, my Google-ing doesn't turn up any meaningful results.
Thanks everyone!
PS: I figure this is messy and not the way this should be done. But I have no choice in how the software puts data in my database. I simply have to use what I get. So... whether this is the "right" way or the "wrong" way, I need a solution. :)
you could do something like this using dynamic sql..
CREATE PROCEDURE dbo.usp_SpatialData_GetByID
(
#ID INT
)
AS
BEGIN
DECLARE #SQL NVARCHAR(MAX),
#Selects NVARCHAR(MAX) = 'SELECT Name, Geometry, ''<<TableName>>'' AS Source FROM <<TableName>>'
SELECT #SQL = COALESCE(#SQL + ' UNION ALL ', '') + REPLACE(#Selects, '<<TableName>>', TableName)
FROM dtSpatialDataTables
WHERE ID = #ID
EXEC(#SQL)
END
GO
I feel like you left out filtering of the Geometry tables somewhere so you might have to add a filter to the #Selects statement
I have multi databases with same structure its name like that "Client1234" the different in numbers beside "client" i have table called "Transactions" inside each database and i want to run query to get count all raws in "transactions" table in all databases.
also when i select database i need to check it has the client word and it has numbers beside the word.
Try to use sp_msforeachdb stored procedure like so:
create table #temp ([rows] int, [client] varchar(100))
exec sp_msforeachdb '
if ''?'' like ''Client%'' and exists(select * from ?.sys.tables t where t.name = ''Transactions'')
begin
insert into #temp select count(*), ''?'' from ?..Transactions
end
'
select * from #temp
drop table #temp
You can use dynamic SQL to create these queries:
select 'select count(*) from ' + name + '.dbo.transactions'
from master..sysdatabases
where name like 'Client%'
and isnumeric(substring(name,6,1))
This would return a result set with each row being a SQL query to count a specific database. It could be consumed by a programming language, used as a cursor, etc.. If you provide more detail I may be able to provide a better example.
When using Fosco's method, it is a good idea to put in brackets [] around the database name:
SELECT 'SELECT count(*) FROM ' + '[' + name + ']' + '.dbo.transactions'
FROM master..sysdatabases
WHERE name like 'Client%' and isnumeric(substring(name,6,1))
If the name and number of the databases you wish to query is not known beforehand then you can only do this by using a dynamic query. You'll need to generate a script like
SELECT COUNT(*) FROM Client1.dbo.Transactions
SELECT COUNT(*) FROM Client2.dbo.Transactions
...
Of course you need to have your appropriate permissions in place for each database.
It looks like #temptables created using dynamic SQL via the EXECUTE string method have a different scope and can't be referenced by "fixed" SQLs in the same stored procedure.
However, I can reference a temp table created by a dynamic SQL statement in a subsequence dynamic SQL but it seems that a stored procedure does not return a query result to a calling client unless the SQL is fixed.
A simple 2 table scenario:
I have 2 tables. Let's call them Orders and Items. Order has a Primary key of OrderId and Items has a Primary Key of ItemId. Items.OrderId is the foreign key to identify the parent Order. An Order can have 1 to n Items.
I want to be able to provide a very flexible "query builder" type interface to the user to allow the user to select what Items he want to see. The filter criteria can be based on fields from the Items table and/or from the parent Order table. If an Item meets the filter condition including and condition on the parent Order if one exists, the Item should be return in the query as well as the parent Order.
Usually, I suppose, most people would construct a join between the Item table and the parent Order tables. I would like to perform 2 separate queries instead. One to return all of the qualifying Items and the other to return all of the distinct parent Orders. The reason is two fold and you may or may not agree.
The first reason is that I need to query all of the columns in the parent Order table and if I did a single query to join the Orders table to the Items table, I would be repoeating the Order information multiple times. Since there are typically a large number of items per Order, I'd like to avoid this because it would result in much more data being transfered to a fat client. Instead, as mentioned, I would like to return the two tables individually in a dataset and use the two tables within to populate a custom Order and child Items client objects. (I don't know enough about LINQ or Entity Framework yet. I build my objects by hand). The second reason I would like to return two tables instead of one is because I already have another procedure that returns all of the Items for a given OrderId along with the parent Order and I would like to use the same 2-table approach so that I could reuse the client code to populate my custom Order and Client objects from the 2 datatables returned.
What I was hoping to do was this:
Construct a dynamic SQL string on the Client which joins the orders table to the Items table and filters appropriate on each table as specified by the custom filter created on the Winform fat-client app. The SQL build on the client would have looked something like this:
TempSQL = "
INSERT INTO #ItemsToQuery
OrderId, ItemsId
FROM
Orders, Items
WHERE
Orders.OrderID = Items.OrderId AND
/* Some unpredictable Order filters go here */
AND
/* Some unpredictable Items filters go here */
"
Then, I would call a stored procedure,
CREATE PROCEDURE GetItemsAndOrders(#tempSql as text)
Execute (#tempSQL) --to create the #ItemsToQuery table
SELECT * FROM Items WHERE Items.ItemId IN (SELECT ItemId FROM #ItemsToQuery)
SELECT * FROM Orders WHERE Orders.OrderId IN (SELECT DISTINCT OrderId FROM #ItemsToQuery)
The problem with this approach is that #ItemsToQuery table, since it was created by dynamic SQL, is inaccessible from the following 2 static SQLs and if I change the static SQLs to dynamic, no results are passed back to the fat client.
3 around come to mind but I'm look for a better one:
1) The first SQL could be performed by executing the dynamically constructed SQL from the client. The results could then be passed as a table to a modified version of the above stored procedure. I am familiar with passing table data as XML. If I did this, the stored proc could then insert the data into a temporary table using a static SQL that, because it was created by dynamic SQL, could then be queried without issue. (I could also investigate into passing the new Table type param instead of XML.) However, I would like to avoid passing up potentially large lists to a stored procedure.
2) I could perform all the queries from the client.
The first would be something like this:
SELECT Items.* FROM Orders, Items WHERE Order.OrderId = Items.OrderId AND (dynamic filter)
SELECT Orders.* FROM Orders, Items WHERE Order.OrderId = Items.OrderId AND (dynamic filter)
This still provides me with the ability to reuse my client sided object-population code because the Orders and Items continue to be returned in two different tables.
I have a feeling to, that I might have some options using a Table data type within my stored proc, but that is also new to me and I would appreciate a little bit of spoon feeding on that one.
If you even scanned this far in what I wrote, I am surprised, but if so, I woul dappreciate any of your thoughts on how to accomplish this best.
You first need to create your table first then it will be available in the dynamic SQL.
This works:
CREATE TABLE #temp3 (id INT)
EXEC ('insert #temp3 values(1)')
SELECT *
FROM #temp3
This will not work:
EXEC (
'create table #temp2 (id int)
insert #temp2 values(1)'
)
SELECT *
FROM #temp2
In other words:
Create temp table
Execute proc
Select from temp table
Here is complete example:
CREATE PROC prTest2 #var VARCHAR(100)
AS
EXEC (#var)
GO
CREATE TABLE #temp (id INT)
EXEC prTest2 'insert #temp values(1)'
SELECT *
FROM #temp
1st Method - Enclose multiple statements in the same Dynamic SQL Call:
DECLARE #DynamicQuery NVARCHAR(MAX)
SET #DynamicQuery = 'Select * into #temp from (select * from tablename) alias
select * from #temp
drop table #temp'
EXEC sp_executesql #DynamicQuery
2nd Method - Use Global Temp Table:
(Careful, you need to take extra care of global variable.)
IF OBJECT_ID('tempdb..##temp2') IS NULL
BEGIN
EXEC (
'create table ##temp2 (id int)
insert ##temp2 values(1)'
)
SELECT *
FROM ##temp2
END
Don't forget to delete ##temp2 object manually once your done with it:
IF (OBJECT_ID('tempdb..##temp2') IS NOT NULL)
BEGIN
DROP Table ##temp2
END
Note: Don't use this method 2 if you don't know the full structure on database.
I had the same issue that #Muflix mentioned. When you don't know the columns being returned, or they are being generated dynamically, what I've done is create a global table with a unique id, then delete it when I'm done with it, this looks something like what's shown below:
DECLARE #DynamicSQL NVARCHAR(MAX)
DECLARE #DynamicTable VARCHAR(255) = 'DynamicTempTable_' + CONVERT(VARCHAR(36), NEWID())
DECLARE #DynamicColumns NVARCHAR(MAX)
--Get "#DynamicColumns", example: SET #DynamicColumns = '[Column1], [Column2]'
SET #DynamicSQL = 'SELECT ' + #DynamicColumns + ' INTO [##' + #DynamicTable + ']' +
' FROM [dbo].[TableXYZ]'
EXEC sp_executesql #DynamicSQL
SET #DynamicSQL = 'IF OBJECT_ID(''tempdb..##' + #DynamicTable + ''' , ''U'') IS NOT NULL ' +
' BEGIN DROP TABLE [##' + #DynamicTable + '] END'
EXEC sp_executesql #DynamicSQL
Certainly not the best solution, but this seems to work for me.
I would strongly suggest you have a read through http://www.sommarskog.se/arrays-in-sql-2005.html
Personally I like the approach of passing a comma delimited text list, then parsing it with text to table function and joining to it. The temp table approach can work if you create it first in the connection. But it feel a bit messier.
Result sets from dynamic SQL are returned to the client. I have done this quite a lot.
You're right about issues with sharing data through temp tables and variables and things like that between the SQL and the dynamic SQL it generates.
I think in trying to get your temp table working, you have probably got some things confused, because you can definitely get data from a SP which executes dynamic SQL:
USE SandBox
GO
CREATE PROCEDURE usp_DynTest(#table_type AS VARCHAR(255))
AS
BEGIN
DECLARE #sql AS VARCHAR(MAX) = 'SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = ''' + #table_type + ''''
EXEC (#sql)
END
GO
EXEC usp_DynTest 'BASE TABLE'
GO
EXEC usp_DynTest 'VIEW'
GO
DROP PROCEDURE usp_DynTest
GO
Also:
USE SandBox
GO
CREATE PROCEDURE usp_DynTest(#table_type AS VARCHAR(255))
AS
BEGIN
DECLARE #sql AS VARCHAR(MAX) = 'SELECT * INTO #temp FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE = ''' + #table_type + '''; SELECT * FROM #temp;'
EXEC (#sql)
END
GO
EXEC usp_DynTest 'BASE TABLE'
GO
EXEC usp_DynTest 'VIEW'
GO
DROP PROCEDURE usp_DynTest
GO