SQL Server - Select

In this article

Overview

You can use this Snap to fetch data from an SQL Server database by providing the database and table details. Queries produced by the Snap have the following format:

SELECT [output fields] FROM [table] WHERE [where clause] ORDER BY [ordering] LIMIT [limit] OFFSET [offset]
  • JSON paths can be used in a query and will have values from an incoming document substituted into the query. However, documents missing values for a given JSON path will be written to the Snap's error view. After a query is executed, the query's results are merged into the incoming document overwriting any existing keys' values. The original document is output if there are no results from the query.

  • This Snap supports SQL Server 2008 or higher version. 

  • The sub-millisecond time accuracy for all date/time data types is not supported.

  • The Where clause can only use variables, not constants or pipeline parameters. An example of a Where clause is: SALARY =$SALARY (here we use the SALARY variable of the input document).

Snap Type

SQL Server - Select Snap is a Read-type Snap that executes SQL SELECT statement.

Prerequisites

None.

Support for Ultra Pipelines

  • Works in Ultra pipelines.

  • Pipelines fail in the execution mode whenever a value is set in the Limit Offset field.

Limitations & Known Issues

None.

Snap Views

Type

Format

Number of Views

Examples of Upstream and Downstream Snaps

Description

Type

Format

Number of Views

Examples of Upstream and Downstream Snaps

Description

Input

Document

  • Min: 0

  • Max: 1

  • Mapper Snap

This Snap allows none or one input view. If the input view is defined, then the where clause can substitute incoming values for a given expression (in such as to use it as a lookup).

Output

Document

  • Min: 1

  • Max: 2

  • Join Snap

This Snap has one output view by default and produces one document for each row in the table. A second view can be added to show the metadata for the table as a Document. The metadata document can then be fed into the second input view of SQL Server - Insert or Bulk Load Snap so that the table is created in SQL Server with a similar schema as the source table.

This Snap produces the records from the database on its output view, which a downstream Snap can then process. 

Error

Error handling is a generic way to handle errors without losing data or failing the Snap execution. You can handle the errors that the Snap might encounter when running the Pipeline by choosing one of the following options from the When errors occur list under the Views tab:

  • Stop Pipeline Execution: Stops the current pipeline execution if the Snap encounters an error.

  • Discard Error Data and Continue: Ignores the error, discards that record, and continues with the remaining records.

  • Route Error Data to Error View: Routes the error data to an error view without stopping the Snap execution.

Learn more about Error handling in Pipelines.

Snap Settings

  • Asterisk (*): Indicates a mandatory field.

  • Suggestion icon (): Indicates a list that is dynamically populated based on the configuration.

  • Expression icon (): Indicates whether the value is an expression (if enabled) or a static value (if disabled). Learn more about Using Expressions in SnapLogic.

  • Add icon (): Indicates that you can add fields in the field set.

  • Remove icon (): Indicates that you can remove fields from the field set.

Field Name

Field Type

Description

Label*

 

Default Value: SQL Server - Select
Example: SQL Server - Select

String

Specify the name for the Snap. You can modify this to be more specific, especially if you have more than one of the same Snap in your pipeline.

Schema Name

 

Default Value: N/A
Example: schema_demo

String/Expression/Suggestion

Specify the database schema name. In case it is not defined, then the suggestion for the Table Name retrieves all tables names of all schemas. The property is suggestible and will retrieve available database schemas during suggest values..

 

Table Name*

 

Default Value: N/A
Example: employees_table

String/Expression/Suggestion

Specify the table to execute the select query on.

Where Clause 

 

Default Value: N/A
Example: SELECT * FROM employees WHERE salary > 50000

String/Expression/Suggestion

Specify the WHERE clause of the SELECT statement. This supports document value substitution (such as $person.firstname is substituted with the value found in the incoming document at the path). However, you cannot use a value substitution after "IS" or "is" word.

Examples:

Without using expressions

  • EmpId = 12 

  • email = 'you@example.com'

Using expressions

  • "EMPNO=$EMPNO and ENAME=$EMPNAME"

  • email = $email 

  • emp=$emp

  • "emp='" + $emp + "'"

  • "EMPNO=" + $EMPNO + " and ENAME='" + $EMPNAME+ "'"

Using expressions that join strings together to create SQL queries or conditions has a potential SQL injection risk and is hence unsafe. Ensure that you understand all implications and risks involved before using concatenation of strings with '=' Expression enabled. 

Order By 

Use this fieldset to specify the columns in the order in which you want to sort the database. The default database sort order will be used.

Column Names

 

Default Value: N/A
Example: name

String/Expression

Specify the column names.

Limit Offset

 

Default Value: N/A
Example: 0

Integer/Expression

Specify the offset for the limit clause. This is where the result set should start. Starting row for the query.

Limit Rows 

 

Default Value: N/A
Example: 10

Integer/Expression

Specify the number of rows to return from the query.

Query Hints

 

Default Value: N/A
Example: OPTION (USE HINT ('DISABLE_OPTIMIZER_ROWGOAL'))

String/Expression

Specify the hints to customize and optimize the database engine in processing the query statement.

Output fields

Use this fieldset to specify the output fields for SQL SELECT statement.

Output Field

 

Default Value: N/A
Example: email, address, first, last

String/Expression

Specify or select output field names for SQL SELECT statement. To select all fields, leave it at default.

 

Fetch Output Fields In Schema

 

Default Value: Deselected

Checkbox

Select this check box to include only the selected fields or columns in the Output Schema (second output view). If you do not provide any Output fields, all the columns are visible in the output.
If you provide output fields, we recommend you to select Fetch Output Fields In Schema checkbox.

 

Pass-through 

 

Default Value: Selected

Checkbox

Select this checkbox to pass the input document through the output view under the key 'original'. 

 

Ignore empty result

 

Default Value: Deselected

Checkbox

Select this checkbox if you do not want to write to the output view when a SELECT operation does not produce any result or is empty.
If you do not select this property and select the Pass through checkbox, the input document is passed through to the output view.

Auto Commit

 

Default Value: False
Example: True

Dropdown list

Select one of the options for this property to override the state of the Auto commit property on the account. The Auto commit at the Snap-level has three values: True, False, and Use account setting. The expected functionality for these modes are:

  •  True - The Snap will execute with auto-commit enabled regardless of the value set for Auto commit in the Account used by the Snap.

  •  False - The Snap will execute with auto-commit disabled regardless of the value set for Auto commit in the Account used by the Snap.

  • Use account setting - The Snap will execute with Auto commit property value inherited by the Account used by the Snap.

Match data types

 

Default Value: Deselected

Checkbox

This property applies only when the Output fields property is provided with any field value(s).

If this property is selected, the Snap tries to match the output data types same as when the Output fields property is empty (SELECT * FROM ...). The output preview would be in the same format as the one when SELECT * FROM is implied and all the contents of the table are displayed.

Number of Retries

 

Default Value: 0
Example: 3

Integer/Expression

Specify the maximum number of attempts to be made to receive a response. The request is terminated if the attempts do not result in a response.

Retry Interval (seconds)

 

Default Value: 1
Example:  10

Integer/Expression

Specify the time interval between two successive retry requests. A retry happens only when the previous attempt resulted in an exception.

 

Staging mode

 

Default Value: In memory
Example: On disk

Dropdown list

Required when the value in the Number of retries field is greater than 0. 

Specify the location from the following options to store input documents between retries:

  • In memory: The query results are stored in the Snaplex memory. If the query is too large to fit in the memory space, it may cause the Snap to fail, choose the On disk option.

  • On disk: The query results are stored on the disk in a temporary (tmp) directory that is managed by the SnapLogic platform. This directory is deleted automatically when the Snap terminates.

Option for Unique Identifier Column

 

Default Value: Convert to lower case
Example: Convert to upper case

Dropdown list

This propery applies only when the Snap returns the unique identifier (GUID) in the output.

Specify the unique identifier is stored in the database using an internal format and when it is displayed in the output, it is converted to a string and gets displayed in upper case for HEX characters. Select either of the following options to change the case type. Available options are:

  • Convert to lower case: Modifies the output string to lower case.

  • Convert to upper case: Modifies the output string to upper case.

Snap Execution

 

Default Value: Validate & Execute
Example: Execute only

Dropdown list

Select one of the following three modes in which the Snap executes:

  • Validate & Execute: Performs limited execution of the Snap, and generates a data preview during Pipeline validation. Subsequently, performs full execution of the Snap (unlimited records) during Pipeline runtime.

  • Execute only: Performs full execution of the Snap during Pipeline execution without generating preview data.

  • Disabled: Disables the Snap and all Snaps that are downstream from it.

Examples

Fetch employee details from a table in the SQL Server database

This example pipeline demonstrates how to retrieve employee details from the Employee_Demo table.

ex-sql-server-pipeline-overview.png

Configure the Mapper Snap with the Employee name and map it to the target column Emp_Name.

Configure the SQL Server- Select Snap to retrieve the specified employee details (from the "Employee_Demo" table) and Where clause "Emp_Name" = $Emp_Name.

On validation, you can view the employee details in the output preview.

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