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Нашёл 3 млн ответов for 'college strategies UNION ALL SELECT NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL-- NIwX'.

A name for the null pointer: nullptr (revision
A null pointer constant is an integral constant expression (expr.const) rvalue of integer type that evaluates to zero. Two null pointer values of the same type shall compare equal. The conversion of a null pointer constant to a pointer to cv-qualified type is a single conver-sion, and not the sequence of...

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2431.pdf

Inserting NULL values into a table and Selecting NULL values
select * from Employee1; -- Employee1 table does NOT have FK constraint superssn to PK ssn, so any value including NULL or ' ' will be accepted but NULL is taken as missing Insert Into Employee1 Values ('James', 'X', 'Brog1', '888660001','10-Nov-27','450 Stone, Houston, TX', 'M','55000', Null,'1')

http://cis.csuohio.edu/~sschung/cis430/HandlingNULLvalues.pdf

Nulls Make Things Easier?
NULL represents unknown, not applicable, or unassigned. It has no data type, so comparing it to xed values always returns NULL. WITH ordertest AS ( SELECT NULL UNION ALL SELECT 2 UNION ALL SELECT 1 UNION ALL SELECT NULL.

https://momjian.us/main/writings/pgsql/nulls.pdf

Nulls in SQL
• What is the effect of operations with null? • What about selection condition age=20 when age is NULL? • SQL use 3 truth values: true, false, unknown. Queries with NULL. The WHERE condition for tuples in a query answer must evaluate to TRUE / 1. • SELECT e.name FROM Emp e.

https://www.cs.rutgers.edu/~borgida/cs336/SQL2.Sp17.pdf

TTCN-3 Quick Reference Card
DESCRIPTION manage use of altstep (activate/deactivate); null is concrete default value TTCN-3 TYPE boolean integer float objid bitstring octetstring record record of set set of enumerated union type enumerated { NULL }.

https://blukaktus.com/TTCN3QRC_viewme.pdf

1'))) UNION ALL SELECT NULL, Concatenated SQL query# AND...
ORDER BY clause brute-forcing NULL brute-forcing Sequential number brute-forcing. The number of columns in the SELECT statement is fewer than the number of columns that you want to inject. Front Range OWASP Conference, Denver (USA).

https://www.owasp.org/images/e/ed/SQLinjectionNotOnly.pdf

Rela7onal Model (Chapter 2) | Null value
Wouldn’t return the instructor with NULL salary (if any). Use predicates to only select “matching” pairs: select * from instructor i, department d Suppose a tuple occurs m times in r and n times in s, then, it occurs: ● m + n times in r union all s ● min(m,n) times in r...

https://www.cs.umd.edu/class/fall2015/cmsc424/lecture-relational.pdf

Using the Set Operators | UNION ALL
When multiple SELECT queries are joined using UNION operator, Oracle displays the combined result from all the compounded SELECT queries,after removing all duplicates and in sorted order ascendingbydefault, without ignoring the NULL values.

https://www.tutorialspoint.com/sql_certificate/pdf/using_the_set_operators.pdf

SQL - unions clause
The SQL UNION clause/operator is used to combine the results of two or more SELECT statements without returning any duplicate rows. To use UNION, each SELECT must have the same number of columns selected, the same number of column expressions, the...

http://www.tutorialspoint.com/sql/pdf/sql-unions-clause.pdf

SQL Injection
1234' and account=NULL; -- For mysql, there must be white space after --. You are identified as name userid. 1234' or 1=1 union select null from balances; -- The used SELECT statements have a different number of columns.

https://www.cs.montana.edu/courses/csci476/topics/sql_injection.pdf