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DECODE is a function in Oracle and is used to provide if-then-else type of logic to SQL. It is not available in MySQL or SQL Server. The syntax for DECODE is:
SELECT DECODE ( "column_name", "search_value_1", "result_1",
"search_value" is the value to search for, and "result" is the value that is displayed.
For example, assume we have the following Store_Information table,
if we want to display 'LA' for 'Los Angeles', 'SF' for 'San Francisco', 'SD' for 'San Diego', and 'Others' for all other cities, we would issue the following SQL,
SELECT DECODE (Store_Name,
'Los Angeles', 'LA',
'San Francisco', 'SF',
'San Diego', 'SD',
'Others') Area, Sales, Txn_Date
"Area" is the name given to the column with the DECODE statement.
To achieve what DECODE does in MySQL and SQL Server, we would use the CASE function.