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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;
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.
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') OR SELECT 1 FROM DUAL WHERE DECODE(NULL, NULL, '1', '0') = '1' Both will evaluate nulls as being equal.
DROP TABLE null_test_tab; CREATE TABLE null_test_tab ( id NUMBER, col1 VARCHAR2(10), col2 VARCHAR2(10), col3 VARCHAR2(10), col4 VARCHAR2(10) ); INSERT INTO null_test_tab values (1, 'ONE', 'TWO', 'THREE', 'FOUR'); INSERT INTO null_test_tab values (2, NULL, 'TWO', 'THREE', 'FOUR'); INSERT INTO null_test_tab values (3, NULL, NULL, 'THREE', 'FOUR ...
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.
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.
