Read selected columns (performance optimization)

By default, all column values are returned in the result set. You can instruct the ServiceNow API to send only specific columns by setting the Fields parameter in the WITH clause. This significantly speeds up the response.

Standard SQL query example

This is the base query accepted by the connector. To execute it in SQL Server, you have to pass it to the Data Gateway via a Linked Server. See how to accomplish this using the examples below.

SELECT number,name FROM incident WITH (Fields='number,name') --Setting Fields parameter will speed up the query

Using OPENQUERY in SQL Server

SELECT * FROM OPENQUERY([LS_TO_SERVICENOW_IN_GATEWAY], 'SELECT number,name FROM incident WITH (Fields=''number,name'') --Setting Fields parameter will speed up the query')

Using EXEC in SQL Server (handling larger SQL text)

The major drawback of OPENQUERY is its inability to incorporate variables within SQL statements. This often leads to the use of cumbersome dynamic SQL (with numerous ticks and escape characters).

Fortunately, starting with SQL 2005 and onwards, you can utilize the EXEC (your_sql) AT [LS_TO_SERVICENOW_IN_GATEWAY] syntax.

DECLARE @MyQuery NVARCHAR(MAX) = 'SELECT number,name FROM incident WITH (Fields=''number,name'') --Setting Fields parameter will speed up the query'
EXEC (@MyQuery) AT [LS_TO_SERVICENOW_IN_GATEWAY]