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PL/SQL / Exceptions

User-defined exception

Learn User-defined exception in PL/SQL through a focused explanation, a dedicated construct-specific example, an engineering boundary, and a mastery check.

10 min read • Intermediate

User-defined exception is an atomic PL/SQL topic inside Exceptions. This lesson focuses on how the User-defined exception construct is written, what it changes, and when it is the right tool.

Trace the example line by line. Identify the exact syntax for User-defined exception, 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

plsql-04-02-user-defined-exception.sql
plsql Try It Live 
DECLARE e_invalid EXCEPTION; v_n NUMBER:=-1; BEGIN IF v_n<0 THEN RAISE e_invalid; END IF; EXCEPTION WHEN e_invalid THEN DBMS_OUTPUT.PUT_LINE('invalid'); END; /
Edge case / engineering note

For User-defined exception, 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.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

Lesson quizzes

User-defined exception Mastery Check →
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