Column 'mary' does not exist

Question

i'm doing a simple query here and it returns that column 'Mary' does not exist:

SELECT  telephone.telephonenumber as tel
FROM    person, telephone
WHERE   person.idperson = telephone.idperson
AND person.personname = ‘Mary’;

Can someone explain what can be happening? I don't want Mary as a column, but as a value.

Thanks in advance, Gabriel

Answer 1

Use plain single quotes to delimit a string literal 'Mary' not smart quotes ‘Mary’