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15 Μαρ 2012 · select decode(type_id, null, 'Unknown', type_id), name, count(*) from. (. select 'asdf' type_id, 'name1' name from dual union all. select 'asdf' type_id, 'name2' name from dual union all. select null type_id, 'name3' name from dual. ) test_table. group by type_id,name;
1 Ιουν 2023 · Oracle DECODE Function with NULL Values. As I mentioned above, the Oracle DECODE function is an exception to other functions in how it handles NULL values. It treats a NULL expression and NULL search as equal (so NULL == NULL). So, this example will return 1: SELECT DECODE(NULL, NULL, 1, 0) FROM DUAL; The CASE statement treats NULL values as ...
9 Ιαν 2014 · Could anyone tell me which of the following statements would perform better? SELECT 1 FROM DUAL WHERE NVL (NULL, '-1') = NVL (NULL, '-1') SELECT 1 FROM DUAL WHERE DECODE (NULL, NULL, '1', '0') = '1'. Both will evaluate nulls as being equal.
Oracle DECODE() function and NULL. NULL cannot be compared to anything even NULL. However, DECODE() function treats two null values are being equal. The following statement returns the string Equal: SELECT DECODE (NULL, NULL, 'Equal', 'Not equal') FROM dual; Code language: SQL (Structured Query Language) (sql)
The DECODE function can be thought of as an inline IF statement. DECODE takes three or more expressions as arguments. Each expression can be a column, a literal, a function, or even a subquery. Let's look at a simple example using DECODE: SELECT lname, DECODE(manager_emp_id, NULL, 'HEAD HONCHO', 'WORKER BEE') emp_type FROM employee; .
This Oracle tutorial explains how to use the Oracle / PLSQL DECODE function with syntax and examples. The Oracle / PLSQL DECODE function has the functionality of an IF-THEN-ELSE statement.
DECODE compares expr to each search value one by one. If expr is equal to a search, then Oracle Database returns the corresponding result. If no match is found, then Oracle returns default. If default is omitted, then Oracle returns null.
