Tds

MSSQL / TDS Database driver for Elixir.

NOTE:

Since TDS version 2.0, tds_ecto package is deprecated, this version supports ecto_sql since version 3.1.0.

Please check out the issues for a more complete overview or CHANGELOG.md.

Usage

Add Tds as a dependency in your mix.exs file.

def deps do
  [{:tds, "~> 2.0"} ]
end

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 form "denst 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 single execution mode can be set at the time and SQL will probably use single execution plan (since it is NOT estimated by checking data density!).

Connecting to SQL Instances

Tds supports SQL instances by passing instance: "instancename" to the connection options. Since v1.0.16, additional connection parameters are:

• :set_language - check stored procedure output exec sp_helplanguage name column value should be used here
• :set_datefirst - number in range 1..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_uncommited | :read_commited | :repeatable_read | :snapshot | :serializable
• :set_allow_snapshot_isolation - 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.

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}
time	{0, 37, 14}
datetime	{{2013, 10, 12}, {0, 37, 14}}
uuid	<<160,238,188,153,156,11,78,248,187,109,107,185,189,56,10,17>>

Currently unsupported: User-Defined Types, XML

Contributing

Clone and compile Tds with:

git clone https://github.com/livehelpnow/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.

SQL Server Setup

The tests require an sql server database to be available on localhost.

If you have Docker installed, you can use the official SQL Server Docker image. To start the container, run:

./docker-mssql.sh

If you prefer to install SQL Server directly on your computer, you can find installation instructions here:

• Windows
• Linux

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.

License

Copyright 2014, 2015, 2017 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

http://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.