select a,b,null,null from table1 union select null,null,c,d from table2 union select null,null,null
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
Postgres is the database Can I use a NULL value for a IN clause? example: … I want to limit to these four values. I have tried the above statement and it doesn't work...
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...
Different ways to replace NULL in sql server - Part 15 - Продолжительность: 11:42 kudvenkat 257 102 просмотра.
Null may refer to: Null (SQL) (or NULL), a special marker and keyword in SQL indicating that something has no value. Null character, the zero-valued ASCII character, also designated by NUL, often used as a terminator, separator or filler. This symbol has no visual representation.
NULL может означать следующее: - NULL (Си и Си++) — в языках программирования Си и C++ означает нулевой указатель; аналог для ссылок в Java — null (указателей в Java нет вообще) . - NULL (SQL) — специальное значение (псевдозначение) , которое может быть записано в поле...
null definition: The definition of null is a zero value, or is something that is no longer valid or relevant
NULL is a special value that signifies 'no value'. Comparing a column to NULL using the = operator
How to count and retrieve null and not null on same column in MySQL?