-----Original Message-----
>From: Burak Serdar <bser...@ieee.org>
>Sent: Jul 22, 2019 11:55 AM
>To: Robert Engels <reng...@ix.netcom.com>
>Cc: Tong Sun <suntong...@gmail.com>, golang-nuts <golang-nuts@googlegroups.com>
>Subject: Re: [go-nuts] Variable life time -- sql.DB connection defer closing
>question
>
>On Mon, Jul 22, 2019 at 10:37 AM Robert Engels <reng...@ix.netcom.com> wrote:
>>
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>> >From: Burak Serdar <bser...@ieee.org>
>> >Sent: Jul 22, 2019 11:13 AM
>> >To: Tong Sun <suntong...@gmail.com>
>> >Cc: golang-nuts <golang-nuts@googlegroups.com>
>> >Subject: Re: [go-nuts] Variable life time -- sql.DB connection defer
>> >closing question
>> >
>> >On Mon, Jul 22, 2019 at 9:35 AM Tong Sun <suntong...@gmail.com> wrote:
>> >>
>> >> All SQL DB statements need a sql.DB connection:
>> >>
>> >> var conn *sql.DB = ...
>> >> defer conn.Close()
>> >>
>> >> statement, err := conn.Prepare(SQL)
>> >>
>> >>
>> >> My question is, if I want to reuse the `conn` variable later on in the
>> >> same function,
>> >>
>> >> conn, err = sql.Open("mssql", NewConnString)
>> >
>> >If you didn't close conn here, then it will leak. The defer will close
>> >the second connection, not the first.
>> >You can add a second defer after opening the second connection. Or,
>> >use a different variable and defer closing of that as well.
>> >
>> >Closing the first connection manually before opening the second won't
>> >work. The first defer will try to close the first connection. Defer
>> >evaluates its arguments when it is declared, not when it runs.
>> >
>> >
>> >>
>> >>
>> >> Do I need to put another `defer conn.Close()` after it, or the first
>> >> `defer conn.Close()` still applies? Or I should call `conn.Close()`
>> >> explicitly beforehand?
>> >>
>> >> thanks
>> >>
>> >> --
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>> >
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>>
>> I don't think that is true. The first defer will be scheduled with the first
>> conn arg (since it is evaluated at call time). You need another defer after
>> the second open. You will end up with Close being called twice from defer
>> which is what you want.
>
>
>I thought that's what I said as well. What part is wrong?
>
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I think it was this statement:
>> If you didn't close conn here, then it will leak. The defer will close
>> the second connection, not the first.
The first defer closes the first conn. A second defer is needed to close the
second conn.
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