### Database Schema:
CREATE TABLE unemployed (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE disabled (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE male (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE no_payment_due (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	bool	TEXT	NULL,
	foreign key (bool) references bool (name),
	foreign key (name) references person (name)
);

CREATE TABLE enrolled (
	name	TEXT	NOT NULL	PRIMARY KEY,
	school	TEXT	NOT NULL	PRIMARY KEY,
	month	INTEGER	NOT NULL	DEFAULT 0,
	foreign key (name) references person (name)
);

CREATE TABLE longest_absense_from_school (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	month	INTEGER	NULL	DEFAULT 0,
	foreign key (name) references person (name)
);

CREATE TABLE bool (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY
);

CREATE TABLE enlist (
	name	TEXT	NOT NULL,
	organ	TEXT	NOT NULL,
	foreign key (name) references person (name)
);

CREATE TABLE filed_for_bankrupcy (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY,
	foreign key (name) references person (name)
);

CREATE TABLE person (
	name	TEXT	NOT NULL	DEFAULT ''	PRIMARY KEY
);

### User's Query:
Calculate the ratio of unemployed students who have never been absent from school.

### Extra Knowledge:
ratio = CONCAT(DIVIDE(MULTIPLY(COUNT(unemployed.name WHERE month = 0), 100), COUNT(month)),'%'); unemployed students who have never been absent from school refers to (unemployed.name WHERE month = 0);
SELECT CAST(SUM(IIF(T2.month = 0, 1, 0)) AS REAL) * 100 / COUNT(T1.name) FROM unemployed AS T1 INNER JOIN longest_absense_from_school AS T2 ON T2.name = T1.name