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CICS QUERY - Query

CICS QUERY provides query management capabilities, enabling query processing and output processing in CICS environments. It provides efficient query capabilities for CICS applications.

What is CICS QUERY?

CICS QUERY provides query management capabilities, enabling query processing and output processing. It provides efficient query capabilities, allowing applications to manage query operations.

Command Syntax

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EXEC CICS QUERY
    [RESP(response-code)]
    [RESP2(response-code-2)]
END-EXEC.

Parameters Explained

RESP Parameters

Response codes returned by the command:

  • RESP: Primary response code - indicates the success or failure of the query operation
  • RESP2: Secondary response code - provides additional error information when RESP indicates failure
  • Always check these codes for command success before proceeding with data processing
  • Handle command failures appropriately to prevent application errors

Query Types

1. Basic Queries

  • Basic queries: Standard query operations that handle simple querying without special formatting
  • Mapped queries: Query operations that use predefined field mappings to structure query data
  • Unmapped queries: Raw query operations that handle unstructured querying without predefined field mappings
  • Custom queries: Specialized query operations designed for specific application requirements

2. Advanced Queries

  • Advanced queries: Complex query operations that handle sophisticated querying processing and validation
  • Secure queries: Query operations that include encryption and security features for sensitive querying
  • Encrypted queries: Query operations that automatically encrypt query data
  • Compressed queries: Query operations that handle compressed querying streams and automatically compress query data

3. Specialized Queries

  • Specialized queries: Query operations tailored for specific protocols or communication methods
  • High-performance queries: Optimized query operations designed for maximum throughput and efficiency
  • Low-latency queries: Query operations optimized for minimal delay and real-time processing requirements
  • High-throughput queries: Query operations designed to handle large volumes of querying efficiently

Implementation Example

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WORKING-STORAGE SECTION.
01 WS-RESPONSE            PIC S9(8) COMP.
01 WS-RESPONSE2           PIC S9(8) COMP.
 
PROCEDURE DIVISION.
    * Query operation
    EXEC CICS QUERY
        RESP(WS-RESPONSE)
        RESP2(WS-RESPONSE2)
    END-EXEC.
    
    IF WS-RESPONSE NOT EQUAL DFHRESP(NORMAL)
        EXEC CICS WRITE OPERATOR
            TEXT('QUERY command failed')
        END-EXEC
        EXEC CICS RETURN END-EXEC
    END-IF.
    
    * Query operation completed successfully
    * Continue processing

Query Processing

1. Query Preparation

Query preparation includes:

  • Query validation - ensuring the query operation is properly configured and authorized
  • Query formatting - preparing data structures and buffers for query data
  • Query encoding - setting up proper character encoding and data transformation
  • Query processing - initializing the query operation and preparing for querying

2. Query Transmission

Query transmission includes:

  • Query routing - directing query data to the appropriate processing location
  • Query delivery - ensuring query data reaches the correct destination within the application
  • Transmission confirmation - verifying that query was completed successfully
  • Error handling - managing transmission failures and implementing retry mechanisms

3. Output Management

Output management includes:

  • User management - handling user sessions and maintaining connection state
  • Output formatting - structuring query data for presentation or further processing
  • User experience - ensuring smooth data flow and responsive application behavior
  • Performance optimization - maximizing query efficiency and minimizing resource usage

Common Response Codes

Success Response Codes

  • NORMAL (0): Query operation completed successfully - querying was completed without errors
  • QUERY (4): Query operation completed - operation completed with query-specific status

Error Response Codes

  • INVREQ (16): Invalid request - the query operation parameters are incorrect or unauthorized
  • NOTFND (20): Resource not found - the specified query resource does not exist
  • LENGERR (22): Length error - the query data length exceeds expected limits
  • QUERY (24): Query error - a query-specific error occurred during the operation

Best Practices

1. Query Preparation

  • Prepare query appropriately - ensure all necessary resources and configurations are in place
  • Validate query content - verify that query data meets expected format and quality standards
  • Handle different query types - implement flexible processing to accommodate various querying formats
  • Ensure query integrity - maintain data consistency and prevent corruption during querying

2. Error Handling

  • Check all response codes - always examine both RESP and RESP2 for complete error information
  • Handle query failures - implement appropriate recovery mechanisms for failed query operations
  • Implement retry logic - provide automatic retry capabilities for transient failures
  • Log error conditions - maintain detailed logs for troubleshooting and monitoring purposes

3. Performance Optimization

  • Minimize query operations - reduce unnecessary query calls to improve overall performance
  • Use efficient query formats - choose appropriate data formats to minimize processing overhead
  • Optimize user updates - streamline user interface updates to reduce response time
  • Manage user resources - efficiently allocate and manage system resources for query operations

Explain It Like I'm 5 Years Old

Imagine you're asking a question:

When you want to know something, you ask a question. If you ask the question, you get an answer. If you don't ask the question, you don't get an answer.

CICS QUERY is like asking a question. The computer program asks a question and gets an answer. If it asks the question, it gets an answer. If it doesn't ask the question, it doesn't get an answer.

Just like you ask questions, the computer program asks questions!

Exercises

Exercise 1: Query Operation

Write a CICS QUERY command to perform a query operation.

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EXEC CICS QUERY
    RESP(WS-RESPONSE)
    RESP2(WS-RESPONSE2)
END-EXEC.

Exercise 2: Query Processing

How would you implement comprehensive query processing that handles different query types and requirements?

Answer: Identify different query types and appropriate handling, implement query validation and encoding, handle different query types and capabilities, implement proper error handling for query failures, optimize query operations for performance, and maintain query integrity throughout the process.

Quiz

Question 1

What is the primary purpose of CICS QUERY?

Answer: B) To provide query management capabilities

Question 2

Which parameter specifies the response code?

Answer: A) RESP

Related Concepts

CICS Query Processing

Query processing and output in CICS

CICS User Management

User management and user interaction in CICS

CICS Output Processing

Output processing and query display in CICS