mainframe Online Quiz - 16

In COBOL, a program cannot cancel itself or be cancelled by its own subroutines. The CANCEL statement must be executed by a program at a higher level in the calling hierarchy. This prevents attempting to release resources and code that are currently in use.

COBOL REDEFINES allows alternative data definitions for the same storage area. A group containing only alphabetic fields can only be redefined by a group containing both alphabetic and numeric fields, because this provides compatible storage and allows for more flexible data interpretation while maintaining character compatibility.

In COBOL, group moves are always processed as alphanumeric (category alphanumeric) operations, regardless of whether the elementary items within the group are numeric, alphabetic, or alphanumeric. The group is treated as a single character string, moving data byte-by-byte without numeric editing or conversion processing.

In IBM VSAM, the maximum number of alternative indexes (AIXs) that can be defined for a single base cluster is 253, making the stored choice correct.

In COBOL, the REPLACING phrase of the COPY statement allows text substitutions within the copied source code, enabling the reuse of the same copy library member with modified values.

RETURN CODE is the standard mechanism for passing completion status back from COBOL programs to JCL. While DD NAME and SYSIN pass data the other way (JCL to program), RETURN CODE specifically passes values from the executing program back to JCL for conditional job control.

In COBOL, the INDEX command creates an index for a table that can then be used by the SEARCH statement to efficiently locate specific table entries. The SEARCH operation requires an index to perform optimized lookups through the table.

In VSAM, a PATH defines the logical relationship between an Alternate Index (AIX) and its Base Cluster. This allows alternate access sequences to the same data.

OPTIONAL specifies that a file may not be present at job execution time. For input files (READ mode), this prevents ABEND if the file is missing. Output files with optional status would create runtime errors if referenced but absent.

SQL is a comprehensive language that can create databases, update tables with INSERT/UPDATE, and drop views with DROP VIEW. However, SQL has no 'REVERSE TABLE' command - reversing table order is done through queries with ORDER BY, not a DDL operation.

COUNT(*) with SELECT returns the total number of rows in a table. The asterisk ensures all rows are counted regardless of NULL values in any column.

SELECT is the fundamental SQL statement for retrieving data from databases. OPEN, GET, and EXTRACT are not standard SQL commands for this purpose.

The basic SELECT syntax is 'SELECT column_name FROM table_name'. This directly retrieves all values from the specified column.

The SELECT DISTINCT statement is the standard SQL syntax used to return only unique (different) values from a query, filtering out duplicate rows. SELECT UNIQUE is an older, non-standard synonym supported by some databases, but DISTINCT is the primary standard keyword.

All four options are valid JOIN types in SQL. LEFT JOIN returns all rows from left table plus matching right table rows. RIGHT JOIN returns all rows from right table plus matching left table rows. FULL JOIN returns all rows when there's a match in either table. SELF JOIN joins a table to itself. All are standard SQL JOIN types.

The UNION operator in SQL combines the result sets of two or more SELECT statements and automatically removes duplicate rows, selecting only distinct values by default. To retain duplicates, UNION ALL must be used. Therefore, the statement is true.

Constraints can be added at table creation time using CREATE TABLE with constraints like PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, or NOT NULL. However, constraints can also be added AFTER table creation using ALTER TABLE statements, making the statement false.

In relational database design, the primary key of a referenced table becomes a foreign key in the referencing table. The question is slightly ambiguous as the primary key itself is a primary key, but in the context of referencing, it acts as a foreign key. An alternate or alias key is incorrect.

SUM() is the aggregate function that returns the total (sum) of values in a numeric column. COUNT() returns the number of rows, not a sum. GROUP BY is used for grouping rows, not aggregation. MAX() returns only the maximum value, not the total.

In REXX, multiple instructions on the same line must be separated by semicolons (;), not commas. This is a fundamental syntax rule in REXX - the semicolon is the instruction terminator. Option B correctly identifies that commas are NOT proper separators. The other options are correct: REXX is case-insensitive (A false), programs conventionally start with /* REXX */ comment (C false), and commas are continuation indicators (D false). REXX's simple syntax makes it popular, but the semicolon rule for multi-line instructions is strict.