자연 조인 NATURAL JOIN 문서의 검증 코드다.
-- 실행: docker exec -i vault-pg psql -U postgres -v ON_ERROR_STOP=1 -q -f - < 이 파일
-- 65.자연 조인 NATURAL JOIN 검증
-- PostgreSQL 16에서 실행한다. 모든 단언을 통과하면 마지막 줄에 ALL CHECKS PASSED가 나온다.
SET client_min_messages TO WARNING;
DROP SCHEMA IF EXISTS natural_join CASCADE;
CREATE SCHEMA natural_join;
SET search_path TO natural_join;
-- COMPANY 스키마와 상태 (Elmasri 그림 5.5~5.7).
-- 상태에 (888665555, 20, NULL)이 있어 Hours에는 NOT NULL을 걸지 않았다.
-- 서로 가리키는 외래 키(EMPLOYEE.Dno <-> DEPARTMENT.Mgr_ssn)는 커밋할 때 검사하도록 미뤘다.
CREATE TABLE EMPLOYEE (Fname VARCHAR(15) NOT NULL, Minit CHAR, Lname VARCHAR(15) NOT NULL, Ssn CHAR(9) NOT NULL,
Bdate DATE, Address VARCHAR(30), Sex CHAR, Salary DECIMAL(10,2), Super_ssn CHAR(9), Dno INT NOT NULL,
PRIMARY KEY (Ssn), FOREIGN KEY (Super_ssn) REFERENCES EMPLOYEE(Ssn) DEFERRABLE INITIALLY DEFERRED);
CREATE TABLE DEPARTMENT (Dname VARCHAR(15) NOT NULL, Dnumber INT NOT NULL, Mgr_ssn CHAR(9) NOT NULL, Mgr_start_date DATE,
PRIMARY KEY (Dnumber), UNIQUE (Dname),
FOREIGN KEY (Mgr_ssn) REFERENCES EMPLOYEE(Ssn) DEFERRABLE INITIALLY DEFERRED);
ALTER TABLE EMPLOYEE ADD FOREIGN KEY (Dno) REFERENCES DEPARTMENT(Dnumber) DEFERRABLE INITIALLY DEFERRED;
CREATE TABLE DEPT_LOCATIONS (Dnumber INT NOT NULL, Dlocation VARCHAR(15) NOT NULL,
PRIMARY KEY (Dnumber, Dlocation), FOREIGN KEY (Dnumber) REFERENCES DEPARTMENT(Dnumber));
CREATE TABLE PROJECT (Pname VARCHAR(15) NOT NULL, Pnumber INT NOT NULL, Plocation VARCHAR(15), Dnum INT NOT NULL,
PRIMARY KEY (Pnumber), UNIQUE (Pname), FOREIGN KEY (Dnum) REFERENCES DEPARTMENT(Dnumber));
CREATE TABLE WORKS_ON (Essn CHAR(9) NOT NULL, Pno INT NOT NULL, Hours DECIMAL(3,1),
PRIMARY KEY (Essn, Pno), FOREIGN KEY (Essn) REFERENCES EMPLOYEE(Ssn), FOREIGN KEY (Pno) REFERENCES PROJECT(Pnumber));
CREATE TABLE DEPENDENT (Essn CHAR(9) NOT NULL, Dependent_name VARCHAR(15) NOT NULL, Sex CHAR, Bdate DATE,
Relationship VARCHAR(8),
PRIMARY KEY (Essn, Dependent_name), FOREIGN KEY (Essn) REFERENCES EMPLOYEE(Ssn));
BEGIN;
INSERT INTO EMPLOYEE VALUES
('John','B','Smith','123456789','1965-01-09','731 Fondren, Houston, TX','M',30000,'333445555',5),
('Franklin','T','Wong','333445555','1955-12-08','638 Voss, Houston, TX','M',40000,'888665555',5),
('Alicia','J','Zelaya','999887777','1968-01-19','3321 Castle, Spring, TX','F',25000,'987654321',4),
('Jennifer','S','Wallace','987654321','1941-06-20','291 Berry, Bellaire, TX','F',43000,'888665555',4),
('Ramesh','K','Narayan','666884444','1962-09-15','975 Fire Oak, Humble, TX','M',38000,'333445555',5),
('Joyce','A','English','453453453','1972-07-31','5631 Rice, Houston, TX','F',25000,'333445555',5),
('Ahmad','V','Jabbar','987987987','1969-03-29','980 Dallas, Houston, TX','M',25000,'987654321',4),
('James','E','Borg','888665555','1937-11-10','450 Stone, Houston, TX','M',55000,NULL,1);
INSERT INTO DEPARTMENT VALUES ('Research',5,'333445555','1988-05-22'),
('Administration',4,'987654321','1995-01-01'), ('Headquarters',1,'888665555','1981-06-19');
INSERT INTO DEPT_LOCATIONS VALUES (1,'Houston'),(4,'Stafford'),(5,'Bellaire'),(5,'Sugarland'),(5,'Houston');
INSERT INTO PROJECT VALUES ('ProductX',1,'Bellaire',5),('ProductY',2,'Sugarland',5),('ProductZ',3,'Houston',5),
('Computerization',10,'Stafford',4),('Reorganization',20,'Houston',1),('Newbenefits',30,'Stafford',4);
INSERT INTO WORKS_ON VALUES ('123456789',1,32.5),('123456789',2,7.5),('666884444',3,40.0),('453453453',1,20.0),
('453453453',2,20.0),('333445555',2,10.0),('333445555',3,10.0),('333445555',10,10.0),('333445555',20,10.0),
('999887777',30,30.0),('999887777',10,10.0),('987987987',10,35.0),('987987987',30,5.0),('987654321',30,20.0),
('987654321',20,15.0),('888665555',20,NULL);
INSERT INTO DEPENDENT VALUES ('333445555','Alice','F','1986-04-05','Daughter'),
('333445555','Theodore','M','1983-10-25','Son'),('333445555','Joy','F','1958-05-03','Spouse'),
('987654321','Abner','M','1942-02-28','Spouse'),('123456789','Michael','M','1988-01-04','Son'),
('123456789','Alice','F','1988-12-30','Daughter'),('123456789','Elizabeth','F','1967-05-05','Spouse');
COMMIT;
-- 1. 이름을 바꾼 표 하나를 괄호로 한 번 더 싼 꼴: PostgreSQL 16은 구문 오류
DO $$ DECLARE ok boolean := false; BEGIN
BEGIN
EXECUTE $q$ SELECT Fname, Lname, Address
FROM (EMPLOYEE NATURAL JOIN (DEPARTMENT AS DEPT (Dname, Dno, Mssn, Msdate)))
WHERE Dname = 'Research' $q$;
EXCEPTION WHEN syntax_error THEN ok := true;
END;
ASSERT ok, '안쪽 괄호가 있는 꼴이 구문 오류를 내지 않았다';
END $$;
-- 2. 안쪽 괄호만 뺀 꼴: 열 목록이 붙은 별칭 그대로 돈다
DO $$ BEGIN
ASSERT (SELECT string_agg(Lname, ',' ORDER BY Lname)
FROM (EMPLOYEE NATURAL JOIN DEPARTMENT AS DEPT (Dname, Dno, Mssn, Msdate))
WHERE Dname = 'Research') = 'English,Narayan,Smith,Wong', '자연 조인 결과가 Research 직원 4명이 아니다';
END $$;
-- 3. 자연 조인한 표는 8행 13열, Dno는 한 번만. PostgreSQL은 맞춘 열을 맨 앞에 둔다
CREATE VIEW NJ AS SELECT * FROM (EMPLOYEE NATURAL JOIN DEPARTMENT AS DEPT (Dname, Dno, Mssn, Msdate));
CREATE VIEW JO AS SELECT * FROM (EMPLOYEE JOIN DEPARTMENT ON Dno = Dnumber);
DO $$ BEGIN
ASSERT (SELECT COUNT(*) FROM NJ) = 8, '자연 조인이 8행이 아니다';
ASSERT (SELECT COUNT(*) FROM information_schema.columns
WHERE table_schema = 'natural_join' AND table_name = 'nj') = 13, '자연 조인이 13열이 아니다';
ASSERT (SELECT COUNT(*) FROM information_schema.columns
WHERE table_schema = 'natural_join' AND table_name = 'nj' AND column_name = 'dno') = 1, 'Dno가 한 번이 아니다';
ASSERT (SELECT column_name FROM information_schema.columns
WHERE table_schema = 'natural_join' AND table_name = 'nj' AND ordinal_position = 1) = 'dno',
'첫 열이 dno가 아니다';
ASSERT (SELECT COUNT(*) FROM information_schema.columns
WHERE table_schema = 'natural_join' AND table_name = 'jo') = 14, 'JOIN ON이 14열이 아니다';
END $$;
-- 4. 이름을 맞추지 않으면: 겹치는 이름이 없어 모든 조합, 뜻이 다른 열이 겹치면 엉뚱한 조건
DO $$ BEGIN
ASSERT (SELECT COUNT(*) FROM EMPLOYEE NATURAL JOIN DEPARTMENT) = 24, '24행이 아니다';
ASSERT (SELECT COUNT(*) FROM EMPLOYEE NATURAL JOIN DEPENDENT) = 0, '0행이 아니다';
ASSERT (SELECT COUNT(*) FROM EMPLOYEE JOIN DEPENDENT ON Ssn = Essn) = 7, 'Ssn = Essn 조인이 7행이 아니다';
ASSERT (SELECT COUNT(*) FROM DEPARTMENT NATURAL JOIN DEPT_LOCATIONS) = 5, '5행이 아니다';
END $$;
SELECT 'ALL CHECKS PASSED';