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15 Μαρ 2012 · 3 Answers. Sorted by: 17. 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;
SELECT DECODE (NULL, NULL, 'Equal', 'Not equal') FROM dual; Code language: SQL (Structured Query Language) (sql) In this tutorial, you have learned how to use the Oracle DECODE() function to add procedure if-then-else logic to SQL queries.
The Oracle/PLSQL DECODE function has the functionality of an IF-THEN-ELSE statement. Syntax. The syntax for the DECODE function in Oracle/PLSQL is: DECODE( expression , search , result [, search , result]... [, default] ) Parameters or Arguments. expression. The value to compare.
27 Δεκ 2023 · sql SELECT COUNT(DECODE(Order_Status, 'Delivered', 1)) AS Delivered_Orders, COUNT(DECODE(Order_Status, 'New', 1)) AS New_Orders FROM Orders; In this example, DECODE transforms 'Delivered' status to 1 and other statuses to NULL. Since COUNT ignores NULLs, this gives us the count of 'Delivered' orders.
The DECODE function is not specifically for handling null values, but it can be used in a similar way to the NVL function, as shown by the following example. SQL> SELECT id, DECODE(col1, NULL, 'ZERO', col1) AS output FROM null_test_tab ORDER BY id; ID OUTPUT ----- ----- 1 ONE 2 ZERO 3 ZERO 4 ZERO 4 rows selected. SQL> NVL2
Purpose. 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.
