Escape double quotes in a string

No. Either use verbatim string literals as you have, or escape the ” using backslash. The string has not changed in either case – there is a single escaped ” in it. This is just a way to tell C# that the character is part of the string and not a string terminator.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)