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NEXT and PRIOR
Learn NEXT and PRIOR in PL/SQL through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.
NEXT and PRIOR is an atomic PL/SQL topic inside Collections & Records. This lesson focuses on how the NEXT and PRIOR construct is written, what it changes, and when it is the right tool.
Trace the example line by line. Identify the exact syntax for NEXT and PRIOR, the input state before it runs, and the resulting value, control flow, database state, hardware behavior, or runtime effect afterward. Neighboring lessons use different constructs rather than renamed copies of this one.
Topic-specific example
DECLARE TYPE t IS TABLE OF VARCHAR2(10) INDEX BY PLS_INTEGER; a t; k PLS_INTEGER; BEGIN a(2):='a'; a(7):='b'; k:=a.FIRST; DBMS_OUTPUT.PUT_LINE(a.NEXT(k)); END; /
For NEXT and PRIOR, test the boundary that belongs to this exact feature rather than a generic failure case. Check invalid or empty input, NULL/unknown state, numeric limits, transaction or exception behavior, synthesis/runtime constraints, ownership/permission rules, or backtracking/control-flow effects where they apply.