MySQL Select

Overview

This Snap allows you to fetch data from a database by providing a table name and configuring the connection. The Snap produces the records from the database on its output view which can then be processed by a downstream Snap.

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.

Queries produced by the Snap have an equivalent format:

SELECT * FROM [table] WHERE [where clause] ORDER BY [ordering] LIMIT [limit] OFFSET [offset]

If more powerful functionality is desired, then the Execute Snap should be used.

This is a Read-type Snap.
Works in Ultra Tasks

Hints

Retrieval of 0000-00-00 date time or timestamp values.

You need to set the following on the MySQL account in case you need to deal with 0000-00-00 defined datetime or timestamp values:


Url property name	Url property value
zeroDateTimeBehavior	convertToNull

This will return all 0000-00-00 defined values as null values. The JDBC driver does not support returning 0000-00-00 as timestamp or datetime values.

Prerequisites

A valid account with the required permissions.
Read access to the target MySQL database table.

Snap views


Type	Description	Examples of upstream and downstream Snaps
Input	Optional.This Snap has at most one document input view. If an input document is provided, it can be used to provide values for query parameters.	Mapper Script
Output	Each output document contains a row from the query result set.	JSON Formatter File Writer
Learn more about Error handling.

Snap settings

Legend:

Expression icon (): Allows using pipeline parameters to set field values dynamically (if enabled). SnapLogic Expressions are not supported. If disabled, you can provide a static value.
SnapGPT (): Generates SnapLogic Expressions based on natural language using SnapGPT. Learn more.
Suggestion icon (): Populates a list of values dynamically based on your Snap configuration. You can select only one attribute at a time using the icon. Type into the field if it supports a comma-separated list of values.
Upload : Uploads files. Learn more.

Learn more about the icons in the Snap settings dialog.


Field/Field set	Description
Label `String`	Required.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. Default value: MySQL Select Example: Select-hired-emps
Schema name `String/Expression/ Suggestion`	The database schema name. In case it is not defined, then the suggestion for the Table Name will retrieve all tables names of all schemas. The property is suggestable and will retrieve available database schemas during suggest values. Default value: N/A Example: SYS
Table name `String/Expression/ Suggestion`	Required.The name of table to read from the specified table. Default value: N/A Example: people
Where clause `String/Expression`	The WHERE clause of select statement. This supports document value substitution (such as $person.firstname will be substituted with the value found in the incoming document at the path). Examples: Without using expressions `EmpId = 12` `email = '[email protected]'` Using expressions `"EMPNO=$EMPNO and ENAME=$EMPNAME"` `email = $email` `emp=$emp` `"emp='" + $emp + "'"` `"EMPNO=" + $EMPNO + " and ENAME='" + $EMPNAME+ "'"` CAUTION: 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 `String/Expression/ Suggestion`	Enter in the columns in the order in which you want to order by. The default database sort order will be used. Default value: None Example: name email
Limit offset `Integer`	Starting row for the query. Default value: None Example: 0
Limit rows `Integer`	The maximum number of rows to return. Default value: None Example: 0
Output fields `String/Expression/ Suggestion`	Enter or select output field names for SQL SELECT statement. To select all fields, leave it at default. Default value: None Example: email, address, first, last, etc.
Fetch Output Fields In Schema `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 check box. Default value: Not selected
Pass through `Checkbox`	If checked, the input document will be passed through to the output view under the key 'original'. Default value: Selected
Ignore empty result `Checkbox`	If selected, no document will be written to the output view when a SELECT operation does not produce any result. If this property is not selected and the Pass through property is selected, the input document will be passed through to the output view. Default value: Not selected
Auto commit `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. Default value: False
Number of retries `Integer`	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. If the value is larger than 0, the Snap first downloads the target file into a temporary local file. If any error occurs during the download, the Snap waits for the time specified in the Retry interval and attempts to download the file again from the beginning. When the download is successful, the Snap streams the data from the temporary file to the downstream Pipeline. All temporary local files are deleted when they are no longer needed. Ensure that the local drive has sufficient free disk space to store the temporary local file. Default value: 0 Example: 3
Retry interval (seconds) `Integer`	Specify the time interval between two successive retry requests. A retry happens only when the previous attempt resulted in an exception. Default value: 1 Example: 10
Match data types `Checkbox`	Conditional. 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. Default value: Not selected
Staging mode `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.
Snap execution `Dropdown list`	Choose one of the three modes in which the Snap executes. Available options are: `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.

Note: For the 'Suggest' in the Order by columns and the Output fields properties, the value of the Table name property should be an actual table name instead of an expression. If it is an expression, it will display an error message "Could not evaluate accessor: ..." when the 'Suggest' button is clicked. This is because, at the time the "Suggest" button is clicked, the input document is not available for the Snap to evaluate the expression in the Table name property. The input document is available to the Snap only during the preview or execution time.