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How to run multiptle queries postgresql statements from C#

I am using EntityFramework and code migrations to keep my Postgres database up to date.
Before deployment on a new environment I would like to make sure the database exists and that the user that will execute queries for the application has enough permissions to do this.
So in short I would like to do the following from my Migrations project before running context.Database.Migrate():
Check whether the database exists
If it doesn't exist create it
Create the user if it doesn't exists
Grant permissions to the user
Run migrations
I have two options (I think):
Run multiple statements at once, keeping the logic inside the query itself and avoid having it in code (C#)
Run statements and deciding in code what to do next.
Option 1 has my preference but when I run the statement checking whether the database exists and create it if it doesn't I get an error: CREATE DATABASE cannot be executed from a function.
The query I'm running looks like this:
DO $$
BEGIN
IF NOT EXISTS(SELECT datname FROM pg_database WHERE datname='database_name') THEN
CREATE DATABASE database_name;
END IF;
END
$$
Option 2 would involve running the statement to check if the database exists with the following code:
using (var conn = new NpgsqlConnection("connection"))
{
conn.Open();
var sql = "SELECT 1 FROM pg_database WHERE datname='database_name'";
var command = new NpgsqlCommand(sql, conn);
var dbExists = command.ExecuteScalar();
if(dbExists == null)
{
command = new NpgsqlCommand("CREATE DATABASE database_name", conn);
command.ExecuteNonQuery();
}
conn.Close();
}
The above code works but I think I prefer option 1.
So I have 2 questions:
How can I fix the CREATE DATABASE cannot be executed from a function error.
Is the second option considered 'wrong'?

Why does a tsql stored proceedure that calls sp_who return different results when called through SqlCommnad than it does through SSMS?

I'm trying to write a stored procedure to determine the number of connections on the active database. My stored procedure is currently as follows:
CREATE PROCEDURE [dbo].[GetActiveUsers]
AS
BEGIN
SET NOCOUNT ON;
DECLARE #who TABLE(spid SMALLINT, ecid SMALLINT, [status] NCHAR(30), loginame NCHAR(128), hostname NCHAR(128), blk CHAR(5), dbname NCHAR(128), cmd NCHAR(16), request_id INT);
INSERT INTO #who
exec sp_who 'FMApp'
--SELECT 99,98,'good','person','host','12345','db','1234567890123456',1
SELECT COUNT(*) AS [ActiveUsers] FROM #who;
END
The reason I am putting the results of sp_who into a table variable is so that I can do some further filtering on the results. I've removed the filtering for now for the sake of debugging.
When I call this stored procedure through SQL Server Management Studio it behaves as expected and I get a non zero value. When I call it through C# using a SqlCommand however it always returns zero.
Calling code:
*Note: connectionService.Create returns an open SqlConnection
using (var connection = connectionService.Create())
{
var activeUsersSql = "GetActiveUsers";
using (var command = new SqlCommand(activeUsersSql, connection))
{
command.CommandType = CommandType.StoredProcedure;
using (var reader = command.ExecuteReader())
{
if (reader.Read())
{
activeUsers = reader.GetInt32(0);
}
}
}
}
If I alter my stored procedure to populate my table variable from a source other than sp_who then both the call to SSMS and the call through SqlCommand agree on the result.
CREATE PROCEDURE [dbo].[GetActiveUsers]
AS
BEGIN
SET NOCOUNT ON;
DECLARE #who TABLE(spid SMALLINT, ecid SMALLINT, [status] NCHAR(30), loginame NCHAR(128), hostname NCHAR(128), blk CHAR(5), dbname NCHAR(128), cmd NCHAR(16), request_id INT);
INSERT INTO #who
SELECT 99,98,'good','person','host','12345','db','1234567890123456',1
--exec sp_who 'FMApp'
SELECT COUNT(*) AS [ActiveUsers] FROM #who;
END
Is it an issues of permissions, a restriction on the use of sp_* procedures or am I missing something obvious?

As suggested by #DavidG the issue was one of permissions. Without the VIEW SERVER STATE permission you can only view your own session. The user I was filtering by was different from the one I was running the process as so it always came up as zero.

To view or retrieve results from sp_who/sp_who2 should need VIEW SERVER STATE permission. I you are using administrator account to connect to SQL server via your C# application it should return data. Check the permission assigned with the account that you use to connect to SQL server in your application.
If no permission, user will be able to see only current session.

OracleCommandBuilder.DeriveParameters() throws OracleException: ORA-06564: object does not exist

Using the OracleClient that comes with ADO.NET in .NET Framework, I'm trying to call OracleCommandBuilder.DeriveParameters() method on a procedure in the database, but I keep getting an OracleException with the message: ORA-06564: object CustOrdersOrders does not exist, even though I created the procedure successfully. I'm more familiar with SQL Server, so perhaps I'm missing something here.
SQL
file 1:
create or replace PACKAGE PKGENTLIB_ARCHITECTURE
IS
TYPE CURENTLIB_ARCHITECTURE IS REF CURSOR;
END PKGENTLIB_ARCHITECTURE;
/
file 2
CREATE OR REPLACE PROCEDURE "CustOrdersOrders"(VCUSTOMERID IN Orders.CustomerID%TYPE := 1, CUR_OUT OUT PKGENTLIB_ARCHITECTURE.CURENTLIB_ARCHITECTURE)
AS
BEGIN
OPEN cur_OUT FOR
SELECT
OrderID,
OrderDate,
RequiredDate,
ShippedDate
FROM Orders
WHERE CustomerID = vCustomerId;
END;
/
Both these files were executed in SQL*Plus as #"path\to\file1.sql".
Code
This is using the Enterprise Library Data Access Application Block, which ultimately wraps the ADO.NET API.
DatabaseProviderFactory factory = new DatabaseProviderFactory(...); //this gets a custom configuration source
Database db = factory.Create("OracleTest");
DbCommand storedProcedure = db.GetStoredProcCommand("CustOrdersOrders");
DbConnection connection = db.CreateConnection();
connection.Open();
storedProcedure.Connection = connection;
db.DiscoverParameters(storedProcedure); //this ultimately calls OracleCommandBuilder.DeriveParameters(), which throws the exception.
When I run direct SQL queries using the same connection, they succeed.
More Details
This is actually part of unit tests written for the Data Access Application Block, which I forked here in an attempt to revive this library. That's why it's using the System.Data.OracleClient and not the ODP.NET. The entire set of tests at https://github.com/tsahi/data-access-application-block/blob/master/source/Tests/Oracle.Tests.VSTS/OracleParameterDiscoveryFixture.cs breaks in a similar way.
The tests are running on an Oracle Database XE I installed locally.
Update
Following question by #madreflection, yes, the following code runs correctly:
Database db = DatabaseFactory.CreateDatabase("OracleTest");
string spName = "AddCountry";
DbCommand dbCommand = db.GetStoredProcCommand(spName);
db.AddInParameter(dbCommand, "vCountryCode", DbType.String);
db.AddInParameter(dbCommand, "vCountryName", DbType.String);
db.SetParameterValue(dbCommand, "vCountryCode", "UK");
db.SetParameterValue(dbCommand, "vCountryName", "United Kingdom");
db.ExecuteNonQuery(dbCommand);
using (DataSet ds = db.ExecuteDataSet(CommandType.Text, "select * from Country where CountryCode='UK'"))
{
Assert.IsTrue(1 == ds.Tables[0].Rows.Count);
Assert.AreEqual("United Kingdom", ds.Tables[0].Rows[0]["CountryName"].ToString().Trim());
}
where "AddCountry" is defined as
CREATE OR REPLACE PROCEDURE ADDCOUNTRY
(vCountryCode IN Country.CountryCode%TYPE,
vCountryName IN Country.CountryName%TYPE
)
AS
BEGIN
INSERT INTO Country (CountryCode,CountryName)
VALUES (vCountryCode,vCountryName);
END;
/
It's interesting to note, though, that in this case the OracleDatabase pointed by db has in it's packages list just EntlibTest, defined (if I understand correctly) by
CREATE OR REPLACE PACKAGE EntlibTest AS
PROCEDURE GetProductDetailsById
(vProductID IN NUMBER,vProductName OUT VARCHAR2,vUnitPrice OUT NUMBER);
END EntlibTest;
/
and then there is another file defining the body of this procedure with
CREATE OR REPLACE PACKAGE BODY EntlibTest AS
PROCEDURE GetProductDetailsById
(vProductID IN NUMBER,vProductName OUT VARCHAR2,vUnitPrice OUT NUMBER)
AS
BEGIN
SELECT ProductName,UnitPrice INTO vProductName,vUnitPrice FROM Products where ProductId = vProductId;
END;
END EntlibTest;
/

Parameter '#s' must be defined

I'm having problems to run a script inside a custom action. The script creates and sets up a database in a localhost MySQL server.
Concretely, I have problems with one of my procedures:
DELIMITER $$
CREATE DEFINER=`root`#`localhost` PROCEDURE `UpdateAutoInc`(IN `increment` BIGINT)
BEGIN
SET #s = concat('ALTER TABLE tblactionservices AUTO_INCREMENT ',increment);
PREPARE stmt FROM #s;
EXECUTE stmt;
SET #s = concat('ALTER TABLE tblbannedclient AUTO_INCREMENT ',increment);
PREPARE stmt FROM #s;
EXECUTE stmt;
END$$
DELIMITER ;
In the script, before this procedure, I have 2 other procedures that run perfectly.
The error I get when I install the application is "Parameter '#s' must be defined". Looking for the Internet I found this blog but I added the "Allow User Variables=True;" with no luck. With this piece of text, the script crashes directly on the first procedure. Indeed, it crashes always, no matter what it finds (procedures, tables...). The error I get is absolutely useless "You have an error in your SQL Syntax; check the manual bla bla", so I can't find the problem.
This is the class I'm using to run the script from c#:
private void ExecuteSql(string DatabaseName, string Sql)
{
MySqlConnection connection = new MySqlConnection { ConnectionString = "server=127.0.0.1;User Id=root" };
MySqlCommand command = new MySqlCommand(Sql, connection);
command.Connection.Close();
command.Connection.Open();
try
{
command.ExecuteNonQuery();
}
finally
{
// Closing the connection should be done in a Finally block
command.Connection.Close();
}
}
The script wasn't manually typed but it was automatically generated from PhPMyAdmin. The version of MySQL server is 5.5 and the connector version is 6.5.5.0

Connect to another database in SQL Server instance from within 'Safe' CLR database trigger

I am writing a CLR Update trigger for SQL Server 2008 R2. The trigger needs to write updated values to a table in another database hosted in the same SQL Server instance. When I try to open a connection created with the following connection string from within my trigger I get a "SecurityException":
...new SqlConnection("Data Source=(local);Initial Catalog=[my database];Integrated Security=True")
It is highly desirable that I leave my assembly's permission level as SAFE. I am pretty sure that I'd have to set my assembly's permission level to EXTERNAL_ACCESS to connect to a remote database, but is it possible to connect to another database in the same SQL Server instance with the SAFE permission level?
Thanks.

Yes, it is definitely possible to reference another database in a SQLCLR trigger that resides inside of an Assembly marked as SAFE. The error encountered in the question is due simply to using a regular / external connection string, which requires a PERMISSION_SET of EXTERNAL_ACCESS. But using the in-process / internal connection string of "Context Connection = true;" allows you to run whatever query you want, including a query that references another database via 3-part object name.
I was able to do this with the following code:
Main Table (in TestDB1):
CREATE TABLE dbo.Stuff
(
[Id] INT IDENTITY(1, 1) NOT NULL PRIMARY KEY,
[Something] NVARCHAR(50) NOT NULL
);
Audit Table (in TestDB2):
CREATE TABLE dbo.AuditLog
(
AuditLogID INT IDENTITY(1, 1) NOT NULL PRIMARY KEY,
EventTime DATETIME NOT NULL DEFAULT (GETDATE()),
BeforeValue NVARCHAR(50) NULL,
AfterValue NVARCHAR(50) NULL
);
SQLCLR Trigger on main table (partial code):
string _AuditSQL = #"
INSERT INTO TestDB2.dbo.AuditLog (BeforeValue, AfterValue)
SELECT del.Something, ins.Something
FROM INSERTED ins
FULL OUTER JOIN DELETED del
ON del.Id = ins.Id;
";
SqlConnection _Connection = new SqlConnection("Context Connection = true");
SqlCommand _Command = _Connection.CreateCommand();
_Command.CommandText = _AuditSQL;
try
{
_Connection.Open();
_Command.ExecuteNonQuery();
}
finally
{
_Command.Dispose();
_Connection.Dispose();
}
Test queries:
USE [TestDB1];
SELECT * FROM dbo.Stuff;
---
INSERT INTO dbo.Stuff (Something) VALUES ('qwerty');
INSERT INTO dbo.Stuff (Something) VALUES ('asdf');
SELECT * FROM dbo.Stuff;
SELECT * FROM TestDB2.dbo.AuditLog;
---
UPDATE tab
SET tab.Something = 'dfgdfgdfgdfgdfgdfgd'
FROM dbo.Stuff tab
WHERE tab.Id = 2;
SELECT * FROM dbo.Stuff;
SELECT * FROM TestDB2.dbo.AuditLog;

It looks like it's not possible. However a T-SQL statement can reference another database in the same instance by using [DatabaseName].[dbo].[TableName]. I can do the messy logic in my CLR trigger, then do a final insert into the second database by calling a simple T-SQL stored procedure and passing in parameters.