Dear All:
I have a question, the following is my code:

#light
open System.Collections.Generic
open System.Data
open System.Data.SqlClient

let sql_ConnDB = "server=(local);Integrated Security=True;Database=localDB"
let connDB = new SqlConnection(sql_ConnDB)

let sqlGetTable2 cmdText unwrapping =
use cmd = new SqlCommand(cmdText, connDB)
connDB.Open()
let reader = cmd.ExecuteReader()
seq { while reader.Read() do
yield unwrapping(reader)
reader.Close()
connDB.Close() }

let (aF1, aF2, aF3) = sqlGetTable2 "SELECT TOP 1 Field1, Field2, Field3 FROM TABLE2"
(fun reader -> (reader.String(0), reader.GetDecimal(1), reader.GetInt32(2))))
|> Seq.head

let sqlGet1FRecords cmdText =
use cmd = new SqlCommand(cmdText, connDB)
connDB.Open()
let reader = cmd.ExecuteReader()
seq { while reader.Read() do
yield reader.GetValue(0)
reader.Close()
connDB.Close() }

let field1 = sqlGet1FRecords "SELECT Field1 FROM Table1"
|> Seq.toArray

printfn "Done!"
The Table1 definition:
Create Table Table1(Field1 [nvarchar] (4) not null);
The value in Table1: insert into Table1 Values('AAAA')

The table2 definition:
Create Table Table2 (Field1 [nvarchar] (4), Field2 [money] not null, Field3 [int] not null);
The value in Table2: insert into Table2 Values('AAAA',2.0,20)

The above code each part can run successfully. I mean if I use only
let (aF1, aF2, aF3) = sqlGetTable2 "SELECT TOP 1 Field1, Field2, Field3 FROM TABLE2"
(fun reader -> (reader.String(0), reader.GetDecimal(1),reader.GetInt32(2))))
|> Seq.head

Or let field1 = sqlGet1FRecords "SELECT Field1 FROM Table1"
|> Seq.toArray

But since I need both of them, but when I put them together in the above order: I got run time error:
System.InvalidOperationException was unhandled
Message=The connection was not closed. The connection's current state is open.
Source=System.Data
StackTrace:
at System.Data.ProviderBase.DbConnectionInternal.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
at System.Data.SqlClient.SqlConnection.Open()
at DBI.sqlGet1FRecords(String cmdText) in C:\Temp\DBI.fs:line 36
at <StartupCode$Program>.$DBI$Main.main@() in C:\Temp\DBI.fs:line 45
InnerException:

However, if I switch the order of the program: I put let field1 = …
Before let (aF1, aF2, aF3) = …, then it works.
It seems the code
let sqlGetTable2 cmdText unwrapping =
use cmd = new SqlCommand(cmdText, connDB)
connDB.Open()
let reader = cmd.ExecuteReader()
seq { while reader.Read() do
yield unwrapping(reader)
reader.Close()
connDB.Close() }

can not close the database connection.
Who can provide some idea how to settle down the database connection issue?
My development environment: VS2010 Beta2 with F# 1.9.7.4 and SQL Server 2008 SP1.
Thanks,