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.
Select char_length(cast('123456789 1' as varchar(10))) from rdb$database. Получаем: Exception ... string truncation Т.е. пробел мы обрезать можем, а другие символы нет. Так и должно быть или нет?
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.
2018-12-04 {\x22visitorId\x22: null, \x22pageSize\x22: 36, \x... 2018-12-04 i \x63\x61nt ti\x65n ti\x65n 2018-12-04 \x2f\x01\x69\163\151\x62\x69\154it\171 2018-12-04 \x65m ko th\x65 \.
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...
Эта техника работает, когда веб-приложения напрямую возвращают результат вывода команды SELECT на страницу: с использованием цикла for или похожим способом, так что каждая запись полученной из БД выборки последовательно выводится на страницу.
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
SELECT CAST('abc' AS varchar(5)) COLLATE French_CS_AS. Truncating and rounding results. When converting character or binary expressions (binary, char, nchar, nvarchar, varbinary, or varchar) to an expression of a different data type, the conversion operation could truncate the output data...
R language supports several null-able values and it is relatively important to understand how these values behave, when making data pre-processing and data