### Database Schema:
CREATE TABLE inspection (
	inspection_id	INTEGER	NULL	PRIMARY KEY,
	inspection_date	DATE	NULL,
	inspection_type	TEXT	NULL,
	results	TEXT	NULL,
	employee_id	INTEGER	NULL,
	license_no	INTEGER	NULL,
	followup_to	INTEGER	NULL,
	foreign key (followup_to) references inspection (inspection_id),
	foreign key (employee_id) references employee (employee_id),
	foreign key (license_no) references establishment (license_no)
);

CREATE TABLE inspection_point (
	point_id	INTEGER	NULL	PRIMARY KEY,
	Description	TEXT	NULL,
	category	TEXT	NULL,
	code	TEXT	NULL,
	fine	INTEGER	NULL,
	point_level	TEXT	NULL
);

CREATE TABLE establishment (
	license_no	INTEGER	NULL	PRIMARY KEY,
	dba_name	TEXT	NULL,
	aka_name	TEXT	NULL,
	facility_type	TEXT	NULL,
	risk_level	INTEGER	NULL,
	address	TEXT	NULL,
	city	TEXT	NULL,
	state	TEXT	NULL,
	zip	INTEGER	NULL,
	latitude	REAL	NULL,
	longitude	REAL	NULL,
	ward	INTEGER	NULL
);

CREATE TABLE violation (
	inspection_id	INTEGER	NULL	PRIMARY KEY,
	point_id	INTEGER	NULL	PRIMARY KEY,
	fine	INTEGER	NULL,
	inspector_comment	TEXT	NULL,
	foreign key (point_id) references inspection_point (point_id),
	foreign key (inspection_id) references inspection (inspection_id)
);

CREATE TABLE employee (
	employee_id	INTEGER	NULL	PRIMARY KEY,
	first_name	TEXT	NULL,
	last_name	TEXT	NULL,
	address	TEXT	NULL,
	city	TEXT	NULL,
	state	TEXT	NULL,
	zip	INTEGER	NULL,
	phone	TEXT	NULL,
	title	TEXT	NULL,
	salary	INTEGER	NULL,
	supervisor	INTEGER	NULL,
	foreign key (supervisor) references employee (employee_id)
);

### User's Query:
After Azha Restaurant Inc. passed the inspection on 2010/1/21, when was the follow-up inspection done?

### Extra Knowledge:
Azha Restaurant Inc. refers to dba_name = 'Azha Restaurant Inc.'; on 2010/1/21 refers to inspection_date = '2010-01-21'; follow-up inspection date refers to followup_to
SELECT T1.followup_to FROM inspection AS T1 INNER JOIN establishment AS T2 ON T1.license_no = T2.license_no WHERE T2.dba_name = 'Azha Restaurant Inc.' AND T1.results = 'Pass' AND T1.inspection_date = '2010-01-21'