menu_book Course Curriculum (PL/SQL) expand_more
FIRST and LAST
Learn FIRST and LAST in PL/SQL through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.
FIRST and LAST is an atomic PL/SQL topic inside Collections & Records. This lesson focuses on how the FIRST and LAST construct is written, what it changes, and when it is the right tool.
Trace the example line by line. Identify the exact syntax for FIRST and LAST, 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; BEGIN a(3):='x'; a(9):='y'; DBMS_OUTPUT.PUT_LINE(a.FIRST||','||a.LAST); END; /
For FIRST and LAST, 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.