Exam 1z0-071 topic 1 question 22 discussion

The rules are listed in descending order: Parentheses (as well as brackets in lookup expressions and IN expressions). Note that you can freely add parentheses any time you want to impose an alternative precedence or to make precedence clearer. * / + - = <> < > <= >= IS (IS NULL, IS NOT NULL, IS EMPTY, IS NOT EMPTY) BETWEEN NOT AND OR

|| (OR) doesn't have a highter order of precedence than + (addition). Here I'll show you why: SELECT 1+1||'1.9' AS addition_operator FROM DUAL; --output: 21.9 SELECT '1.9'||1+1 AS or_condition FROM DUAL; --output: 2.91 In the first SELECT statement is first adding up 1+1 (2) and then concatenating with '1.9', making the output '21.9'. Lastly, the second SELECT statement concatenates '1.9' with 1 ('1.91') and then adding up 1, making the output '2.91'. This proves that, in this case, whatever comes first in the statement will be calculated. If there was an order of precedence, the outputs would've been: OR first: '12.9' (1+(1||'1.9')) and '2.91' (('1.91'||1)+1). + first: '21.9' ((1+1)||'1.9') and '1.92' ('1.9'||(1+1)). So the correct answers are C and E.

|| has a higher order of precedence than + (addition).

select '9.9'||1+2 from dual Result 11.91 Contamination is done first

https://docs.oracle.com/cd/E49933_01/server.770/es_eql/src/ceql_expr_precedence_rules.html#:~:text=The%20rules%20are,the%20JOIN%20operators.

CE is correct

This Oracle doc explains between OR, AND, and NOT. https://docs.oracle.com/en/database/other-databases/nosql-database/22.2/sqlreferencefornosql/operator-precedence.html

https://www.tutorialspoint.com/plsql/plsql_operators_precedence.htm