Official | HULFT IoT EdgeStreaming Adapter Reference First Edition: July 1, 2021
Select (1 row)
This operation outputs the operation results of retrieval from a database (select).
This operation specifies the search conditions as input data, and if a single-row record matches the conditions, it outputs the record to the subsequent component.
The result of what is written to the database is output to "metadata\succeeded" of the output schema.
If a single-row record that matches the search conditions can be retrieved, "true" is output.
If a record that matches the search conditions cannot be retrieved, or if multiple records exist that match the search conditions, "false" is output.
The "true" or "false" value that is output to "metadata\succeeded" of the output schema is a character string.
If you want to handle the output value as a boolean value, use the following logic to compare values, and then use the value of the comparison results:
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Condition > Boolean > Boolean Constant
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Condition > String > Equal
You can display the select (1 row) operation screen by displaying the script canvas on the Designer screen, clicking the following items in the following order, and then dragging and dropping the component icon onto the script canvas:
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Tool palette > Database > PostgreSQL > Select(1 row)
Figure 6.11 Select (1 row) operation screen
(1) Field list
This is a list of the fields to configure for the select (1 row) operation.
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Field Name |
Initial Value |
Setting Value |
Omission |
Notes |
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|---|---|---|---|---|---|
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Name |
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Single-byte alphanumeric characters and certain symbols (*1) |
- |
A value that begins with a single-byte alphabetic character |
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|
Input data |
(No input data) |
Name of the input data component |
- |
Select from list (*2) |
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Required settings |
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Destination |
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|
- |
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Table name |
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|
- |
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Schema definition |
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|
- |
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Stream setting |
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Relation-to-Stream Operator |
RSTREAM |
|
✓ |
Select from list |
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Window type |
TUPLES |
|
✓ |
Select from list |
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|
Window |
1 |
From 1 to 2147483646 |
✓ |
Set as integer |
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|
Comment |
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Comment |
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Characters |
✓ |
|
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✓ |
: |
Possible to omit |
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- |
: |
Impossible to omit |
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*1 |
: |
Only "_" (underscore) can be specified. |
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*2 |
: |
When component icons for input or conversion are placed on the script canvas, the options are displayed in the list. |
(2) Description of each field
This section explains each of the fields to configure for the select (1 row) operation.
After changing these settings, click Finish to save the settings.
Click Cancel to discard the changes.
- Name
-
Name of the select (1 row) operation component
Single-byte alphanumeric characters and "_" (underscore) can be used.
Use a value that begins with a single-byte alphabetic character.
- Input data
-
Selection of the component name of the input data for the select (1 row) operation
From the input data component names displayed in the list, select the component name for the select (1 row) operation.
Required settings
- Destination
-
PostgreSQL destination
Select the PostgreSQL destination for the select (1 row) operation.
When you click Add, the PostgreSQL connection settings screen appears.
For details on the PostgreSQL connection settings screen, refer to PostgreSQL connection settings.
When you click Edit list..., the editing screen for the resource list appears.
For details on the editing screen for the resource list, refer to Edit resource list.
- Table name
-
Input data column name
Specify the PostgreSQL table name for the select (1 row) operation.
You can also use Get table list to get a list of table names.
- Schema definition
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PostgreSQL schema definition
Configure the schema of the PostgreSQL that is set as the destination.
You can also use Get column name to get the schema definition.
Stream setting
- Relation-to-Stream Operator
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Method for stream operation
The stream operation converts the results data of relational operations into stream data.
Data such as all data (RSTREAM) or added data (ISTREAM) is output as stream data according to changes in the output relation (*1).
Select from the following methods for stream operation:
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RSTREAM
All data is processed.
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ISTREAM
Only data that differs from the directly preceding data is processed.
If you omit this setting, "RSTREAM" is used to perform the operation for the relation.
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- Window type
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Processing unit for stream operation
Select from the following units for processing with the stream operation:
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TUPLES
Use tuples (*2) for processing.
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SECONDS
Use seconds for processing.
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MILLISECONDS
Use milliseconds for processing.
If you omit this setting, "TUPLES" is selected.
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- Window
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Execution count for stream operation
Specify a number from "1" through "2147483646" for the execution count for the stream operation.
If you omit this setting, "1" is selected.
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*1 |
: |
The operation is executed during conversion processing, and the data that will become the result is extracted as a relation. This relation is called output relation. |
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*2 |
: |
A tuple represents a stream component. A tuple is used as the unit for data that moves the stream. |
Comment
- Comment
-
Comment regarding the select (1 row) operation
You can enter a comment.
Official | HULFT IoT EdgeStreaming Adapter Reference First Edition: July 1, 2021