select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null
Above is two queries with their results merged by a UNION ALL clause. You will notice that the queries return different columns, one called 'departure' and one called 'arrival'.
Then in the second table I have select ..., null as opt from... I know that I could have an empty string with '' as opt however, I don't want an empty string, I really do need it to be 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?
Union select null, null, null, null, null, null, null from information_schema.tables. for a small database containing three tables. this instruction is used in sql injection I tried it and it worked but I didn't really know how it...
What is the difference between … and … and why does the latter not work?
Hours 1 1 2 null null null. The result must be: 3. My query is
Note: A NULL value is different from a zero value or a field that contains spaces. A field with a NULL value is one that has been left
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..?
In C, there appear to be differences between various values of zero -- NULL, NUL and 0. I know that the ASCII character '0' evaluates to 48 or 0x30. The NULL pointer is usually defined as: … Or …