Why do these MySQL queries give different results?

Question

SELECT * FROM tbl_custum_advertisement WHERE 'group' = 1

SELECT * FROM `tbl_custum_advertisement` WHERE `group`=1

Answer 1

You first query is comparing a literal 'group' to a literal 1.

Your second query is comparing the value of the field group to a literal 1.

MySQL uses backticks to indicate fields, and single quotes to indicate strings (or double quotes, actually)

Answer 2

Quotes (') and backticks

`

are different.

'blah' is a literal string. But

`blah`

is a column (or other) name.

'group' = 1 is never true. But a column named group might contain the value 1, so

`group` = 1

could possibly be true.

Answer 3

Backticks (`) are to be used as an identifier for tables and columns

Single quotes (') should be used for strings and string comparisons

Please refer to this question for further understanding

When to use single quotes, double quotes, and backticks in MySQL