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.
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.
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..?
I understand that a char variable can accept a null character(1 byte) i.e; \0 as its value but, I don't understand how a char variable in my application below accepts a pointer(4 bytes)...
What is the difference between … and … and why does the latter not work?
I'm trying to replace the null character with a different value. I would have thought that the following would work but it is unsuccessfull
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 works can somebody help me...
A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field.
In R language, NULL … Continue reading R null values: NULL, NA, NaN, Inf.