DECODE Function

The decode function has the functionality of an IF-THEN-ELSE statement.

The syntax for the decode function is:

decode ( expression , search , result [, search , result]... [, default] )

expression is the value to compare.

search is the value that is compared against expression .

result is the value returned, if expression is equal to search .

default is optional.  If no matches are found, the decode will return default .  If default is omitted, then the decode statement will return null (if no matches are found).

For Example:

You could use the decode function in an SQL statement as follows:

The above decode statement is equivalent to the following IF-THEN-ELSE statement:

IF supplier_id = 10000 THEN

     result := 'Sausage';

ELSIF supplier_id = 10001 THEN

    result := 'Eggs';

ELSIF supplier_id = 10002 THEN

    result := 'Bacon';

ELSE

    result := 'Food';

END IF; 

The decode function will compare each supplier_id value, one by one.

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