### Database Schema:
CREATE TABLE Question (
	questiontext	TEXT	NULL,
	questionid	INTEGER	NULL	PRIMARY KEY
);

CREATE TABLE Answer (
	AnswerText	TEXT	NULL,
	SurveyID	INTEGER	NULL,
	UserID	INTEGER	NULL	PRIMARY KEY,
	QuestionID	INTEGER	NULL	PRIMARY KEY,
	foreign key (QuestionID) references Question (questionid),
	foreign key (SurveyID) references Survey (SurveyID)
);

CREATE TABLE Survey (
	SurveyID	INTEGER	NULL	PRIMARY KEY,
	Description	TEXT	NULL
);

### User's Query:
How many users believed that their productivity is ever affected by a mental health issue overall?

### Extra Knowledge:
Users who believed that their productivity is affected by a mental health issues overall refers to AnswerText = 'Yes' where questionid = 54
SELECT COUNT(T1.UserID) FROM Answer AS T1 INNER JOIN Question AS T2 ON T1.QuestionID = T2.questionid WHERE T2.questionid = 54 AND T1.AnswerText LIKE 'Yes'