How to Solve PLS-00103: Encountered the Symbol When Expecting Once of the Following

The PLS-00103 error is a syntax error in PL/SQL that occurs when the PL/SQL compiler encounters an unexpected symbol while parsing the code. This means that something in the code is incorrectly placed, misspelled, or missing.

This error message is often accompanied by a list of expected symbols, which helps in identifying the issue.

Common Causes and Solutions

1. Missing or Incorrect Keywords

Cause:

Using an incorrect or missing keyword in a PL/SQL block.

Example: Incorrect DECLARE Usage

DECLARE v_name VARCHAR2(50)
BEGIN
    v_name := 'John Doe';
    DBMS_OUTPUT.PUT_LINE(v_name);
END;
/

Error Output:

PLS-00103: Encountered the symbol "BEGIN" when expecting one of the following: := ; not null constant default

Solution:

Add a semicolon (;) after the variable declaration.

DECLARE 
    v_name VARCHAR2(50);  -- Fixed: Added semicolon
BEGIN
    v_name := 'John Doe';
    DBMS_OUTPUT.PUT_LINE(v_name);
END;
/

2. Using a Reserved Keyword as an Identifier

Cause:

Using an Oracle reserved keyword as a variable or table name.

Example: Using SELECT as a Variable Name

DECLARE 
    select VARCHAR2(50);
BEGIN
    select := 'PL/SQL Error';
    DBMS_OUTPUT.PUT_LINE(select);
END;
/

Error Output:

PLS-00103: Encountered the symbol "SELECT" when expecting an identifier

Solution:

Use double quotes or rename the variable.

DECLARE 
    v_select VARCHAR2(50);  -- Fixed: Changed variable name
BEGIN
    v_select := 'PL/SQL Error';
    DBMS_OUTPUT.PUT_LINE(v_select);
END;
/

Or:

DECLARE 
    "SELECT" VARCHAR2(50);  -- Fixed: Used double quotes
BEGIN
    "SELECT" := 'PL/SQL Error';
    DBMS_OUTPUT.PUT_LINE("SELECT");
END;
/

However, using double quotes is not recommended, as it makes maintenance difficult.

3. Missing IS or AS in a Procedure or Function Declaration

Cause:

A stored procedure is declared without IS or AS before the BEGIN block.

Example: Procedure Without IS or AS

CREATE OR REPLACE PROCEDURE my_proc 
BEGIN
    DBMS_OUTPUT.PUT_LINE('Hello');
END;
/

Error Output:

PLS-00103: Encountered the symbol "BEGIN" when expecting one of the following: IS AS AUTHID

Solution:

Add IS or AS after the procedure name.

CREATE OR REPLACE PROCEDURE my_proc IS  -- Fixed: Added IS
BEGIN
    DBMS_OUTPUT.PUT_LINE('Hello');
END;
/

4. Incorrect Usage of IF Statement

Cause:

Not using THEN in an IF statement.

Example: Missing THEN

DECLARE
    v_salary NUMBER := 5000;
BEGIN
    IF v_salary > 4000  -- Missing THEN
        DBMS_OUTPUT.PUT_LINE('High Salary');
    END IF;
END;
/

Error Output:

PLS-00103: Encountered the symbol "DBMS_OUTPUT.PUT_LINE" when expecting one of the following: THEN

Solution:

Add THEN after the IF condition.

DECLARE
    v_salary NUMBER := 5000;
BEGIN
    IF v_salary > 4000 THEN  -- Fixed: Added THEN
        DBMS_OUTPUT.PUT_LINE('High Salary');
    END IF;
END;
/

5. Incorrect Placement of EXCEPTION Block

Cause:

Placing EXCEPTION outside a BEGIN-END block.

Example: Incorrect Exception Placement

DECLARE
    v_number NUMBER := 10;
EXCEPTION
    WHEN OTHERS THEN
        DBMS_OUTPUT.PUT_LINE('An error occurred');
BEGIN
    v_number := v_number / 0;
END;
/

Error Output:

PLS-00103: Encountered the symbol "EXCEPTION" when expecting one of the following: ...

Solution:

Move EXCEPTION inside the BEGIN-END block.

DECLARE
    v_number NUMBER := 10;
BEGIN
    v_number := v_number / 0;
EXCEPTION
    WHEN OTHERS THEN  -- Fixed: Placed inside BEGIN-END
        DBMS_OUTPUT.PUT_LINE('An error occurred');
END;
/

6. Incorrect Loop Syntax

Cause:

Not using LOOP or END LOOP.

Example: Missing LOOP Keyword

DECLARE
    v_counter NUMBER := 1;
BEGIN
    WHILE v_counter <= 5  -- Missing LOOP
        DBMS_OUTPUT.PUT_LINE(v_counter);
        v_counter := v_counter + 1;
    END LOOP;
END;
/

Error Output:

PLS-00103: Encountered the symbol "DBMS_OUTPUT.PUT_LINE" when expecting one of the following: LOOP

Solution:

Add LOOP after the WHILE condition.

DECLARE
    v_counter NUMBER := 1;
BEGIN
    WHILE v_counter <= 5 LOOP  -- Fixed: Added LOOP
        DBMS_OUTPUT.PUT_LINE(v_counter);
        v_counter := v_counter + 1;
    END LOOP;
END;
/

Summary of Solutions

Conclusion

The PLS-00103 error is one of the most common PL/SQL errors, but it is also one of the easiest to fix once you identify the cause. By carefully checking for syntax issues, missing keywords, misplaced statements, and incorrect variable names, you can quickly resolve this error and ensure that your PL/SQL code runs smoothly.