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...
UNION ALL SELECT NULL, *, NULL, NULL FROM email. I understand what this does and why; the hacker needs to create a query that has the same number
(M): SELECT CONCAT(login, password) FROM members. 7. Строки без кавычек Есть несколько
Hours 1 1 2 null null null. The result must be: 3. My query is: select count(distinct hour) from hours; but it returns: 2. I tested also
SELECT m.id, m.name, m.description, m.directions, COUNT(j.markerid) as marker_jingles FROM markers AS m LEFT OUTER JOIN jingles AS j ON j.markerid=m.id WHERE 1. But am a bit stuck because I cannot figure out how to get it to return rows when the COUNT is 0.
SELECT CAST(NULL AS INTEGER) FROM dual; And, if you don't have dual as a table (you probably don't), you can do one of a few things
SELECT ColA FROM TableA WHERE ColA IS NULL. I get 47 rows that have 'NULL' for ColA within TableA. ColA NULL NULL NULL etc...
returns non null values in group */ SELECT COUNT(Col1) FROM ##TestData; Because of this, COUNT, DISTINCT, and NULLs have a special relationship with each other that isn’t always as intuitive as many people think. Whenever using COUNT or DISTINCT, make sure to test with NULLs to make...
· Using SELECT COUNT(*) or SELECT COUNT(1) (which is what I prefer to use) will return the total of all records returned in the result set regardless of NULL values.
Существуют специальные операторы IS NULL и IS NOT NULL, которые позволяют производить сравнения с NULLами.