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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; The CASE statement treats NULL values as ...
This tutorial shows you how to use the Oracle DECODE() function to add the procedural if-then-else logic to SQL queries.
6 Αυγ 2024 · This tutorial provides a comprehensive guide to using the SQL DECODE() function in Oracle. I will also compare DECODE() to CASE WHEN in Oracle and help you understand when to use each function. Finally, I will provide code for the equivalent transformations in SQL Server, PostgreSQL, and MySQL.
9 Ιαν 2014 · SELECT 1 FROM DUAL WHERE NVL (NULL, '-1') = NVL (NULL, '-1') OR SELECT 1 FROM DUAL WHERE DECODE(NULL, NULL, '1', '0') = '1' Both will evaluate nulls as being equal. I was just curious which would perform better as I have to have about 30 of these statements together in a case statement. In my statements the two nulls represent different columns.
31 Ιαν 2013 · Just want to compare one example with "case" and "decode". 1. select decode((select deptno from dept d where d.deptno = e.deptno), 10,'A', 20, 'B', 30, 'REST' ) as test from emp e 2. select (case when (select deptno from dept d where d.deptno = e.deptno) = 10 then 'A' when (select deptno from dept d where d.deptno = e.deptno) = 20 then 'B' else ...
This Oracle tutorial explains how to use the Oracle/PLSQL DECODE function with syntax and examples. Description. 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] )
