--about whether NULL participates in the calculation in the Oracle database, and is validated,

--about whether NULL participates in the calculation in the Oracle database, and is validated,
With TD as (
Select null id,1 name from dual
),
TD1 as
(
Select null id,2 name from dual)

SELECT * from TD, TD1 where NVL (td.id, ' 0.00 ') = ' 0 '

Select ' 1 ' | | ' 0.1 ' from dual
Number
Number, Char
Select To_char (3333.00, ' 999,999,009.00 ') from dual
To_char;
To_date;
To_number;
3333.00
Select To_char (3.00, ' fm9990999 ') from dual
JSP ####,000
Partten = ' ################ #0000 '
3
03
Select NVL (null,0.00) from dual;
Null does not participate in the calculation

= To compare, the two sides of different types, the downward transformation
Select Sysdate from dual where 0 = 0;
Select Sysdate from dual where ' 0 ' = ' 0 ';
Number---Char
Char--number

NVL (td1.id,0);
Null BU Cnayu JIS
GROUP BY
Select SUM (ID) from TD;
1
Select 1+null from dual
Null does not participate in the calculation

--about whether NULL participates in the calculation in the Oracle database, and is validated,