Tds - MSSQL Driver for Elixir
MSSQL / TDS Database driver for Elixir.
NOTE:
Since TDS version 2.0, tds_ecto
package is deprecated, this version supports ecto_sql
since version 3.3.4.
Please check out the issues for a more complete overview. This branch should not be considered stable or ready for production yet.
For stable versions always use hex.pm as source for your mix.exs.
Usage
Add :tds
as a dependency in your mix.exs
file.
def deps do
[
{:tds, "~> 2.0"}
]
end
As of TDS version >= 1.2
, tds can support windows codepages other than windows-1252
(latin1).
If you need such support you will need to include additional dependency {:excoding, "~> 0.1"}
and configure :tds
app to use Excoding
module like this:
import Mix.Config
config :tds, :text_encoder, Excoding
When you are done, run mix deps.get
in your shell to fetch and compile Tds.
Start an interactive Elixir shell with iex -S mix
.
iex> {:ok, pid} = Tds.start_link([hostname: "localhost", username: "test_user", password: "test_password", database: "test_db", port: 4000])
{:ok, #PID<0.69.0>}
iex> Tds.query!(pid, "SELECT 'Some Awesome Text' AS MyColumn", [])
%Tds.Result{columns: ["MyColumn"], rows: [{"Some Awesome Text"}], num_rows: 1}}
iex> Tds.query!(pid, "INSERT INTO MyTable (MyColumn) VALUES (@my_value)",
...> [%Tds.Parameter{name: "@my_value", value: "My Actual Value"}])
%Tds.Result{columns: nil, rows: nil, num_rows: 1}}
Features
- Automatic decoding and encoding of Elixir values to and from MSSQL's binary format
- Support of TDS Versions 7.3, 7.4
Configuration
Example configuration
import Mix.Config
config :your_app, :tds_conn,
hostname: "localhost",
username: "test_user",
password: "test_password",
database: "test_db",
port: 1433
Then using Application.get_env(:your_app, :tds_conn)
use this as first parameter in Tds.start_link/1
function.
There is additional parameter that can be used in configuration and can improve query execution in SQL Server. If you find out that your queries suffer from "density estimation" as described here
You can try switching how tds executes queries as below:
import Mix.Config
config :your_app, :tds_conn,
hostname: "localhost",
username: "test_user",
password: "test_password",
database: "test_db",
port: 1433,
execution_mode: :executesql
This will skip calling sp_prepare
and query will be executed using sp_executesql
instead.
Please note that only one execution mode can be set at a time, and SQL Server will probably
use single execution plan (since it is NOT estimated by checking data density!).
SSL / TLS support
tds >= 2.3.0
supports encrypted connections to the SQL Server.
The following encryption behaviours are currently supported:
:required
: Requires the server to use TLS:on
: Same as required:not_supported
: Indicates to the server that encryption is not supported. If server requires encryption, the connection will not be established.
Currently not supported:
:off
: This setting allows the server to upgrade the connection (if server encryption is:on
or:required
) and only encrypts the LOGIN packet when the server has encryption set to:off
.:client_cert
: This will make the server check the client cerfiticate.
Setting ssl: true
or ssl: false
is also allowed. In that case true
is mapped to :required
and false
to :not_supported
.
config :your_app, :tds_conn,
hostname: "localhost",
username: "test_user",
password: "test_password",
database: "test_db",
ssl: :required,
port: 1433,
execution_mode: :executesql
Connecting to SQL Server Instances
Tds supports SQL Server instances by passing instance: "instancename"
to the connection options.
Since v1.0.16, additional connection parameters are:
:set_language
- check stored procedure outputexec sp_helplanguage
name column value should be used here:set_datefirst
- number in range1..7
:set_dateformat
- atom, one of:mdy | :dmy | :ymd | :ydm | :myd | :dym
:set_deadlock_priority
- atom, one of:low | :high | :normal | -10..10
:set_lock_timeout
- number in milliseconds > 0:set_remote_proc_transactions
- atom, one of:on | :off
:set_implicit_transactions
- atom, one of:on | :off
:set_transaction_isolation_level
- atom, one of:read_uncommitted | :read_committed | :repeatable_read | :snapshot | :serializable
:set_allow_snapshot_isolation
- atom, one of:on | :off
:set_cursor_close_on_commit
- atom, one of:on | :off
:set_read_committed_snapshot
- atom, one of:on | :off
Set this option to enable snapshot isolation on the database level. Requires connecting with a user with appropriate rights. More info here.
Federation Authentication
This Authentication mechanism is not supported. This functionality requires specific environment to be developed.
Data representation
TDS | Elixir |
---|---|
NULL | nil |
bool | true / false |
char | "é" |
int | 42 |
float | 42.0 |
text | "text" |
binary | <<42>> |
numeric | #Decimal<42.0> |
date | {2013, 10, 12} or %Date{} |
time | {0, 37, 14} or {0, 37, 14, 123456} or %Time{} |
smalldatetime | {{2013, 10, 12}, {0, 37, 14}} or {{2013, 10, 12}, {0, 37, 14, 123456}} |
datetime | {{2013, 10, 12}, {0, 37, 14}} or {{2013, 10, 12}, {0, 37, 14, 123456}} or %NaiveDateTime{} |
datetime2 | {{2013, 10, 12}, {0, 37, 14}} or {{2013, 10, 12}, {0, 37, 14, 123456}} or %NaiveDateTime{} |
datetimeoffset(n) | {{2013, 10, 12}, {0, 37, 14}} or {{2013, 10, 12}, {0, 37, 14, 123456}} or %DateTime{} |
uuid | <<160,238,188,153,156,11,78,248,187,109,107,185,189,56,10,17>> |
Currently unsupported: User-Defined Types, XML
Dates and Times
Tds can work with dates and times in either a tuple format or as Elixir calendar types. Calendar types can be enabled in the config with config :tds, opts: [use_elixir_calendar_types: true]
.
Tuple forms:
- Date:
{yr, mth, day}
- Time:
{hr, min, sec}
or{hr, min, sec, fractional_seconds}
- DateTime:
{date, time}
- DateTimeOffset:
{utc_date, utc_time, offset_mins}
In SQL Server, the fractional_seconds
of a time
, datetime2
or datetimeoffset(n)
column can have a precision of 0-7, where the microsecond
field of a %Time{}
or %DateTime{}
struct can have a precision of 0-6.
Note that the DateTimeOffset tuple expects the date and time in UTC and the offset in minutes. For example, {{2020, 4, 5}, {5, 30, 59}, 600}
is equal to '2020-04-05 15:30:59+10:00'
.
UUIDs
MSSQL stores UUIDs in mixed-endian format, and these mixed-endian UUIDs are returned in Tds.Result.
To convert a mixed-endian UUID binary to a big-endian string, use Tds.Types.UUID.load/1
To convert a big-endian UUID string to a mixed-endian binary, use Tds.Types.UUID.dump/1
Contributing
Clone and compile Tds with:
git clone https://github.com/elixir-ecto/tds.git
cd tds
mix deps.get
You can test the library with mix test
. Use mix credo
for linting and
mix dialyzer
for static code analysis. Dialyzer will take a while when you
use it for the first time.
Development SQL Server Setup
The tests require an SQL Server database to be available on localhost. If you are not using Windows OS you can start sql server instance using Docker. Official SQL Server Docker image can be found here.
If you do not have specific requirements on how you would like to start sql server in docker, you can use script for this repo.
$ ./docker-mssql.sh
If you prefer to install SQL Server directly on your computer, you can find installation instructions here:
Make sure your SQL Server accepts the credentials defined in config/test.exs
.
You also will need to have the sqlcmd command line tools installed. Setup instructions can be found here:
Special Thanks
Thanks to ericmj, this driver takes a lot of inspiration from postgrex.
Also thanks to everyone in the Elixir Google group and on the Elixir IRC Channel.
Copyright and License
Copyright (c) 2015 LiveHelpNow
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.