OData Connector - Using T-SQL / Linked Server

T-SQL is a programming language used for managing and querying data in Microsoft SQL Server databases. We provides tools for data integration, automation, and connectivity.

If you want to use T-SQL with ZappySys, you can use our Connector, which allows you to connect to SQL Server databases and execute T-SQL queries from OData.

Create Data Source in ZappySys Data Gateway based on API Driver

Download and install ODBC PowerPack.
Search for gateway in start menu and Open ZappySys Data Gateway:
Go to Users Tab to add our first Gateway user. Click Add; we will give it a name tdsuser and enter password you like to give. Check Admin option and click OK to save. We will use these details later when we create linked server:
Now we are ready to add a data source. Click Add, give data source a name (Copy this name somewhere, we will need it later) and then select Native - ZappySys API Driver. Finally, click OK. And it will create the Data Set for it and open the ZS driver UI.

OdataDSN
When the Configuration window appears give your data source a name if you haven't done that already, then select "OData" from the list of Popular Connectors. If "OData" is not present in the list, then click "Search Online" and download it. Then set the path to the location where you downloaded it. Finally, click Continue >> to proceed with configuring the DSN:

OdataDSN

OData

Now it's time to configure the Connection Manager. Select Authentication Type, e.g. Token Authentication. Then select API Base URL (in most cases, the default one is the right one). More info is available in the Authentication section.

No Authentication [Http]

Fill in all required parameters and set optional parameters if needed:

OdataDSN

OData

No Authentication [Http]

https://services.odata.org/V3/Northwind/Northwind.svc

Optional Parameters
RetryMode	RetryWhenStatusCodeMatch
RetryStatusCodeList	429
RetryCountMax	5
RetryMultiplyWaitTime	True
IgnoreSSLCertificateErrors
SslVersion

Windows Authentication [Http]

Fill in all required parameters and set optional parameters if needed:

OdataDSN

OData

Windows Authentication [Http]

https://services.odata.org/V3/Northwind/Northwind.svc

This Authentication Type has no parameters to fill-in.

Basic Authentication [Http]

Fill in all required parameters and set optional parameters if needed:

OdataDSN

OData

Basic Authentication [Http]

https://services.odata.org/V3/Northwind/Northwind.svc

Required Parameters
UserName	Fill-in the parameter...
Password	Fill-in the parameter...
Optional Parameters
RetryMode	RetryWhenStatusCodeMatch
RetryStatusCodeList	429
RetryCountMax	5
RetryMultiplyWaitTime	True
IgnoreSSLCertificateErrors
SslVersion

NTLM Authentication [Http]

Fill in all required parameters and set optional parameters if needed:

OdataDSN

OData

NTLM Authentication [Http]

https://services.odata.org/V3/Northwind/Northwind.svc

Required Parameters
UserName (i.e. Domain\UserName)	Fill-in the parameter...
Password	Fill-in the parameter...
Optional Parameters
RetryMode	RetryWhenStatusCodeMatch
RetryStatusCodeList	429
RetryCountMax	5
RetryMultiplyWaitTime	True
IgnoreSSLCertificateErrors
SslVersion

Token Authentication [Http]

Fill in all required parameters and set optional parameters if needed:

OdataDSN

OData

Token Authentication [Http]

https://services.odata.org/V3/Northwind/Northwind.svc

Required Parameters
Token	Fill-in the parameter...
Optional Parameters
AuthScheme	Bearer
AuthHeader	Authorization
RetryMode	RetryWhenStatusCodeMatch
RetryStatusCodeList	429
RetryCountMax	5
RetryMultiplyWaitTime	True
IgnoreSSLCertificateErrors
SslVersion

OAuth Connection for OData API [OAuth]

Fill in all required parameters and set optional parameters if needed:

OdataDSN

OData

OAuth Connection for OData API [OAuth]

https://services.odata.org/V3/Northwind/Northwind.svc

Optional Parameters
GrantType	Default
OAuthVersion	Default
ClientId
ClientSecret
UserName
Password
Scope
AuthUrl	https://some-domain.com/api/auth
TokenUrl	https://some-domain.com/api/token
ReturnUrl	https://zappysys.com/oauth
ExtraAttributesForTokenRequest
ExtraAttributesForAuthRequest
DoNotIncludeCredentialsInHeader
DoNotIncludeCredentialsInBody
RenewBeforeSec
ExtraHeaders (e.g. x-hdr1:AAA\|\|x-hdr2:BBB)
ContentType
EnableCodeVerifier
RemoveAuthHeader
CustomAuthHeader
CustomTokenPrefix
RetryMode	RetryWhenStatusCodeMatch
RetryStatusCodeList	429
RetryCountMax	5
RetryMultiplyWaitTime	True
IgnoreSSLCertificateErrors
SslVersion

Once the data source connection has been configured, it's time to configure the SQL query. Select the Preview tab and then click Query Builder button to configure the SQL query:

- OData

OData Connector can be used to integrated any REST API which supports OData Standard. You can view tables, read data from tables using this connector. It also comes with some example OData Services to get started.

OdataDSN
Start by selecting the Table or Endpoint you are interested in and then configure the parameters. This will generate a query that we will use in to retrieve data from OData. Hit OK button to use this query in the next step.
```
SELECT * FROM Customers
```
Some parameters configured in this window will be passed to the OData API, e.g. filtering parameters. It means that filtering will be done on the server side (instead of the client side), enabling you to get only the meaningful data much faster.
Now hit Preview Data button to preview the data using the generated SQL query. If you are satisfied with the result, use this query in :
- OData

OData Connector can be used to integrated any REST API which supports OData Standard. You can view tables, read data from tables using this connector. It also comes with some example OData Services to get started.

OdataDSN
```
SELECT * FROM Customers
```
You can also access data quickly from the tables dropdown by selecting <Select table>.

A WHERE clause, LIMIT keyword will be performed on the client side, meaning that the whole result set will be retrieved from the OData API first, and only then the filtering will be applied to the data. If possible, it is recommended to use parameters in Query Builder to filter the data on the server side (in OData servers).
Click OK to finish creating the data source.

Read data in SQL Server using ZappySys Data Gateway

To read the data in SQL Server, the first thing you have to do is create a Linked Server:

First, let's open SQL Server Management Studio, create a new Linked Server, and start configuring it:

LS_TO_ODATA_IN_GATEWAY

Microsoft OLE DB Driver for SQL Server

localhost,5000

OdataDSN

OdataDSN

Choose SQL Server Native Client 11.0 as Provider if you don't see the option shown above.
Then click on Security option and configure username we created in ZappySys Data Gateway in one of the previous steps:
Optional step. Under the Server Options, Enable RPC and RPC Out and Disable Promotion of Distributed Transactions(MSDTC).

You need to enable RPC Out if you plan to use EXEC(...) AT [LS_TO_ODATA_IN_GATEWAY] rather than OPENQUERY.
If don't enabled it, you will encounter the Server 'LS_TO_ODATA_IN_GATEWAY' is not configured for RPC error.

Query Example:
```
EXEC('SELECT * FROM Customers') AT [LS_TO_ODATA_IN_GATEWAY]
```
If you plan to use 'INSERT INTO <TABLE> EXEC(...) AT [LS_TO_ODATA_IN_GATEWAY]' in that case you need to Disable Promotion of Distributed Transactions(MSDTC).
If don't disabled it, you will encounter the The operation could not be performed because OLE DB provider "SQLNCLI11" for linked server "MY_LINKED_SERVER_NAME" was unable to begin a distributed transaction. error.

Query Example:
```
INSERT INTO dbo.Products
EXEC('SELECT * FROM Customers') AT [LS_TO_ODATA_IN_GATEWAY]
```

Finally, open a new query and execute a query we saved in one of the previous steps:

SELECT * FROM OPENQUERY([LS_TO_ODATA_IN_GATEWAY], 'SELECT * FROM Customers')

Execute query at Linked Server to ZappySys Data Gateway in SSMS

SELECT * FROM OPENQUERY([LS_TO_ODATA_IN_GATEWAY], 'SELECT * FROM Customers')

Create Linked Server using Code

In previous section you saw how to create a Linked Server from UI. You can do similar action by code too (see below). Run below script after changing necessary parameters. Assuming your Data Source name on ZappySys Data Gateway UI is 'OdataDSN'

USE [master]
GO
--///////////////////////////////////////////////////////////////////////////////////////
--Run below code in SSMS to create Linked Server and use ZappySys Drivers in SQL Server
--///////////////////////////////////////////////////////////////////////////////////////

-- Replace YOUR_GATEWAY_USER, YOUR_GATEWAY_PASSWORD
-- Replace localhost with IP/Machine name if ZappySys Gateway Running on different machine other than SQL Server
-- Replace Port 5000 if you configured gateway on a different port


--1. Configure your gateway service as per this article https://zappysys.com/links?id=10036

--2. Make sure you have SQL Server Installed. You can download FREE SQL Server Express Edition from here if you dont want to buy Paid version https://www.microsoft.com/en-us/sql-server/sql-server-editions-express

--Uncomment below if you like to drop linked server if it already exists
--EXEC master.dbo.sp_dropserver @server=N'LS_TO_ODATA_IN_GATEWAY', @droplogins='droplogins'

--3. Create new linked server

EXEC master.dbo.sp_addlinkedserver
    @server = N'LS_TO_ODATA_IN_GATEWAY'  --Linked server name (this will be used in OPENQUERY sql
, @srvproduct=N''
---- For MSSQL 2012,2014,2016 and 2019 use below (SQL Server Native Client 11.0)---
, @provider=N'SQLNCLI11'
---- For MSSQL 2022 or higher use below (Microsoft OLE DB Driver for SQL Server)---
--, @provider=N'MSOLEDBSQL'
, @datasrc=N'localhost,5000' --//Machine / Port where Gateway service is running
, @provstr=N'Network Library=DBMSSOCN;'
, @catalog=N'OdataDSN' --Data source name you gave on Gateway service settings

--4. Attach gateway login with linked server

EXEC master.dbo.sp_addlinkedsrvlogin
@rmtsrvname=N'LS_TO_ODATA_IN_GATEWAY'  --linked server name
, @useself=N'False'
, @locallogin=NULL
, @rmtuser=N'YOUR_GATEWAY_USER' --enter your Gateway user name
, @rmtpassword='YOUR_GATEWAY_PASSWORD'  --enter your Gateway user's password
GO

--5. Enable RPC OUT (This is Optional - Only needed if you plan to use EXEC(...) AT YourLinkedServerName rather than OPENQUERY
EXEC sp_serveroption 'LS_TO_ODATA_IN_GATEWAY', 'rpc', true;
EXEC sp_serveroption 'LS_TO_ODATA_IN_GATEWAY', 'rpc out', true;

--Disable MSDTC - Below needed to support INSERT INTO from EXEC AT statement
EXEC sp_serveroption 'LS_TO_ODATA_IN_GATEWAY', 'remote proc transaction promotion', false;

--Increase query timeout if query is going to take longer than 10 mins (Default timeout is 600 seconds)
--EXEC sp_serveroption 'LS_TO_ODATA_IN_GATEWAY', 'query timeout', 1200;
GO