The CASE statement in PL/SQL is a type of control structure that allows you to execute a sequence of statements based on a condition. It is similar to the IF-THEN-ELSE statement in other programming languages. The CASE statement has two forms: simple and searched. In the simple form, the CASE statement compares an expression to a set of values and returns a result based on the first matching value. In the searched form, the CASE statement evaluates multiple conditions and returns a result based on the first condition that is TRUE.The CASE statement has two forms: simple and searched. The simple CASE statement compares an expression to a set of literal values and returns the result of the first comparison that is TRUE. If no match is found, then the ELSE clause expressions are returned, or NULL if there is no ELSE clause.The searched CASE statement evaluates multiple Boolean expressions and returns the first result that is TRUE. If no match is found, then the ELSE clause expressions are returned, or NULL if there is no ELSE clause.A CASE statement is used to make decisions based on a set of conditions. The CASE statement starts with the keyword CASE, followed by an expression. The expression is compared to the values in each WHEN clause in order until a match is found. If no match is found, the ELSE clause is executed. If there is no ELSE clause and no match is found, nothing is executedThe following example shows how to use the CASE statement:DECLAREgrade char(1);BEGINgrade := 'B';CASE gradeWHEN 'A' THEN dbms_output.put_line('Excellent')WHEN 'B' THEN dbms_output.put_line('Very Good');WHEN 'C' THEN dbms_output.put_line('Good');WHEN 'D' THEN dbms_output.put_line('Fair');WHEN 'F' THEN dbThe CASE statement in Oracle PL/SQL has two forms: simple CASE and searched CASE. Simple CASE evaluates an expression for a match to a set of values, and returns the result corresponding to the first matching value. Searched CASE evaluates multiple Boolean expressions and returns the first result that is TRUE. NULL is not a valid value for either type of CASE expression.