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SQL using If Not Null on a Concatenation - Stack Overflow

stackoverflow.com

If I have the table … This will display Firstname-Middlename-Surname e.g. … The second one (Jane’s) displays correct, however since John doesn’t have a middlename, I want it to ignore the second dash.

sql - Counting null and non-null values in a single... - Stack Overflow

stackoverflow.com

SELECT COUNT(*), 'null_tally' AS narrative FROM us WHERE a IS NULL UNION SELECT COUNT(*), 'not_null_tally' AS narrative FROM

sql - Union to handle NULL values - Stack Overflow

stackoverflow.com

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.

sql injection "union select null" - CodeProject

www.codeproject.com

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...

Confusing SQL error in SELECT NULL, *, NULL, NULL - Stack Overflow

stackoverflow.com

The Background I was trying to solve the fourth realistic mission in hackthissite.org, and couldn't figure out exactly what SQL I should inject into the URL to retrieve the list of emails.

MySQL SQL Injection Practical Cheat Sheet - Perspective Risk

www.perspectiverisk.com

1 UNION ALL SELECT NULL,concat(0x28,column1,0x3a,column2,0x29) FROM database2.table1--. Error Based.

MySQL 8.0 Reference Manual :: B.6.4.3 Problems with NULL Values

dev.mysql.com

An expression that contains NULL always produces a NULL value unless otherwise indicated in the documentation for the operators and functions involved in the expression. All columns in the following example return NULL: Press CTRL+C to copy. mysql> SELECT NULL, 1+NULL, CONCAT('Invisible'...

SQL NULL Values - IS NULL and IS NOT NULL

www.w3schools.com

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 blank during record creation!

Использование значения NULL в условиях поиска | Интерактивный...

www.sql-tutorial.ru

Предикат IS NULL позволяет проверить отсутствие (наличие) значения в полях таблицы. Использование в этих случаях обычных предикатов сравнения может привести к неверным результатам, так как сравнение со значением NULL дает результат UNKNOWN (неизвестно).

Заметка про NULL / Хабр

habr.com

IS NULL вернёт истину, если операнд имеет значение NULL и ложь, если он им не является.

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