decode

1. DECODE Function

The DECODE function in H2 database is used to perform conditional logic and return different values based on specified conditions.

The syntax for the DECODE function in H2 database is as follows:

DECODE(expression, search_value1, result1, search_value2, result2, ..., default_result)

expression: The value to be compared against the search values.
search_value1: The value to search for in the expression.
result1: The value to return if search_value1 matches the expression.
search_value2: The value to search for in the expression.
result2: The value to return if search_value2 matches the expression.
default_result: The value to return if none of the search values match the expression.

The DECODE function returns the result corresponding to the first matching search value. If no match is found, the default result is returned.

The DECODE function in H2 database is similar to the CASE statement and can be used as an alternative for conditional logic.
The number of search value and result pairs can be variable, allowing for multiple conditions to be checked.
If the expression matches multiple search values, the result corresponding to the first match is returned.
If no match is found and no default result is specified, the DECODE function returns NULL.
The DECODE function in H2 database is case-sensitive, so ensure that the search values and expressions match exactly.

Here are a few examples demonstrating the usage of the DECODE function in H2 database:

SELECT DECODE(2, 1, 'One', 2, 'Two', 'Other') AS result;

Output:

result
------
Two

SELECT DECODE('Apple', 'Orange', 'Fruit is Orange', 'Apple', 'Fruit is Apple', 'Other Fruit') AS result;

Output:

result
--------------
Fruit is Apple

SELECT DECODE(5, 1, 'One', 2, 'Two', 'No Match Found') AS result;

Output:

result
----------------
No Match Found