select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null,null,null,e,f from table3.
union all select null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null
I have developed a query, and in the results for the first three columns I get NULL. How can I replace it with 0?
How can I run a MySQL query that selects everything that is not null? It would be something like … Do I just remove the all and go..?
0x31303235343830303536 is NULL - they are just matching the number of columns in your existing query. If you had SELECT * FROM users and users had 4 columns, the UNION must also have 4
I have a table with three fields, FirstName, LastName and Email. Here's some dummy data: … Now, if I do: … Vitals for Joe is null, as there is a single null field. How do you overcome this behaviour?
What is the difference between … and … and why does the latter not work?
SELECT CHAR(0x66) (S) SELECT 0x5045 (this is not an integer it will be a string from Hex) (M) SELECT
Note: A NULL value is different from a zero value or a field that contains spaces.
Даже выражение NULL != NULL не будет истинным, ведь нельзя однозначно сравнить одну неизвестность с другой. Кстати, ложным это выражение тоже не будет, потому что при вычислении условий Oracle не ограничивается состояниями ИСТИНА и ЛОЖЬ.