feat: update structure

cs2102/labs/tutorials/T07.sql

@@ -0,0 +1,160 @@
+CREATE TABLE Offices
+(
+    oid     INTEGER,
+    address VARCHAR(60),
+    PRIMARY KEY (oid)
+);
+
+-- eid = eid of department 's manager
+CREATE TABLE IF NOT EXISTS Departments
+(
+    did     INTEGER,
+    dbudget INTEGER NOT NULL,
+    oid     INTEGER NOT NULL,
+    eid     INTEGER NOT NULL, -- no FK to manager
+    PRIMARY KEY (did),
+    FOREIGN KEY (oid) REFERENCES Offices
+);
+
+CREATE TABLE IF NOT EXISTS Employees
+(
+    eid INTEGER,
+    did INTEGER NOT NULL,
+    PRIMARY KEY (eid),
+    FOREIGN KEY (did) REFERENCES Departments
+);
+
+CREATE TABLE IF NOT EXISTS Engineers
+(
+    eid INTEGER,
+    PRIMARY KEY (eid),
+    FOREIGN KEY (eid) REFERENCES Employees
+);
+
+CREATE TABLE IF NOT EXISTS Managers
+(
+    eid INTEGER,
+    PRIMARY KEY (eid),
+    FOREIGN KEY (eid) REFERENCES Employees
+);
+
+-- eid = eid of project's supervisor
+CREATE TABLE IF NOT EXISTS Projects
+(
+    pid     INTEGER,
+    pbudget INTEGER NOT NULL,
+    eid     INTEGER NOT NULL,
+    PRIMARY KEY (pid),
+    FOREIGN KEY (eid) REFERENCES Managers
+);
+
+CREATE TABLE IF NOT EXISTS WorkType
+(
+    wid       INTEGER,
+    max_hours INTEGER NOT NULL,
+    PRIMARY KEY (wid)
+);
+
+CREATE TABLE IF NOT EXISTS Works
+(
+    pid   INTEGER,
+    eid   INTEGER,
+    wid   INTEGER,
+    hours INTEGER NOT NULL,
+    PRIMARY KEY (pid, eid),
+    FOREIGN KEY (eid) REFERENCES Engineers,
+    FOREIGN KEY (pid) REFERENCES Projects,
+    FOREIGN KEY (wid) REFERENCES WorkType
+        ON DELETE CASCADE
+);
+
+CREATE OR REPLACE FUNCTION not_manager()
+    RETURNS TRIGGER AS
+$$
+DECLARE
+    count NUMERIC;
+BEGIN
+    SELECT COUNT(*) INTO count FROM managers WHERE NEW.eid = Managers.eid;
+    if count > 0 THEN RETURN NULL; ELSE RETURN NEW; END IF;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER non_manager
+    BEFORE INSERT OR UPDATE
+    ON Engineers
+    FOR EACH ROW
+EXECUTE FUNCTION not_manager();
+
+CREATE OR REPLACE FUNCTION check_budget()
+    RETURNS TRIGGER AS
+$$
+DECLARE
+    pbudget     numeric;
+    curr_budget numeric;
+BEGIN
+    SELECT pbudget
+    INTO pbudget
+    FROM projects
+    WHERE pid = NEW.pid;
+
+    SELECT COALESCE(SUM(hours), 0) * 100
+    INTO curr_budget
+    FROM Works
+    WHERE pid = NEW.pid
+      AND eid != NEW.eid;
+    if curr_budget + NEW.hours * 100 > pbudget THEN
+        RETURN (NEW.pid, NEW.eid, NEW.wid, (pbudget - curr_budget) / 100);
+    ELSE
+        RETURN NEW;
+    end if;
+
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER budget_check
+    BEFORE INSERT OR UPDATE
+    ON Works
+    FOR EACH ROW
+EXECUTE FUNCTION check_budget();
+
+CREATE OR REPLACE FUNCTION max_hour_work()
+    RETURNS TRIGGER AS
+$$
+DECLARE
+    max_hrs NUMERIC;
+BEGIN
+    SELECT max_hours INTO max_hrs FROM worktype WHERE wid = NEW.wid;
+    IF NEW.HOURS > max_hrs THEN
+        RETURN (NEW.pid, NEW.eid, NEW.wid, max_hrs);
+    ELSE
+        RETURN NEW;
+    END IF;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER hours_max
+    BEFORE INSERT OR UPDATE
+    ON works
+    FOR EACH ROW
+EXECUTE FUNCTION max_hour_work();
+
+
+
+CREATE OR REPLACE FUNCTION wid_check()
+    RETURNS TRIGGER AS
+$$
+DECLARE
+BEGIN
+    RAISE NOTICE 'some user tried to';
+    RAISE NOTICE 'modify/delete default';
+    RAISE NOTICE 'work type';
+    RETURN NULL;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER check_wid
+    BEFORE UPDATE OR DELETE
+    ON WorkType
+    FOR EACH ROW
+    WHEN (OLD.wid = 0)
+EXECUTE FUNCTION wid_check();