Обновление таблицы со случайным классом

Question

У меня есть функция, предназначенная для присвоения оценок определенным школам в таблице simulated_records, которая основана на количестве студентов и вероятности того, что каждый студент получит конкретную оценку для этой школы. У меня уже есть вся эта вероятность, но я получаю ошибки при попытке обновить таблицу с правильными оценками. Я не знаю, обновляюсь ли я неправильно или помещаю обновление в правильную область.

CREATE FUNCTION assigngrades(probs numeric[], school text, record_id bigint) RETURNS void AS $$ 
DECLARE 
num_grades integer ARRAY[6]; 
found_school school_probs%ROWTYPE; 
num_students simulated_records%ROWTYPE; 
random_record simulated_records%ROWTYPE; 
num_students_int bigint; 



BEGIN 
SELECT INTO found_school * FROM school_probs WHERE school_code = record_id; 
SELECT INTO num_students * FROM simulated_records WHERE school = school_name; 
SELECT COUNT(*) INTO num_students_int FROM simulated_records WHERE school = school; 

num_grades[1] = num_students_int*found_school.probs[1]; 
num_grades[2] = num_students_int*found_school.probs[1]; 
num_grades[3] = num_students_int*found_school.probs[1]; 
num_grades[4] = num_students_int*found_school.probs[1]; 
num_grades[5] = num_students_int*found_school.probs[1]; 
num_grades[6] = num_students_int*found_school.probs[1]; 

FOR i IN 1..num_grades[1] LOOP 

    SELECT INTO random_record * FROM simulated_records WHERE school = school_name ORDER BY RANDOM() LIMIT 1; 
    IF random_record.grade = '-' THEN 
     random_record.grade = 'A'; 

END IF; 
UPDATE simulated_records.grade = random_record.grade; 
END Loop; 

FOR i IN 1..num_grades[2] LOOP 

    SELECT INTO random_record * FROM simulated_records WHERE school = school_name ORDER BY RANDOM() LIMIT 1; 
    IF random_record.grade = '-' THEN 
     random_record.grade := 'A-'; 
END IF; 
UPDATE simulated_records.grade = random_record.grade; 
END Loop; 
FOR i IN 1..num_grades[3] LOOP 

    SELECT INTO random_record * FROM simulated_records WHERE school = school_name ORDER BY RANDOM() LIMIT 1; 
    IF random_record.grade = '-' THEN 
     random_record.grade := 'B+'; 
END IF; 
UPDATE simulated_records.grade = random_record.grade; 
END Loop; 
FOR i IN 1..num_grades[4] LOOP 

    SELECT INTO random_record * FROM simulated_records WHERE school = school_name ORDER BY RANDOM() LIMIT 1; 
    IF random_record.grade = '-' THEN 
     random_record.grade := 'B'; 
END IF; 
UPDATE simulated_records.grade = random_record.grade; 
END Loop; 
FOR i IN 1..num_grades[5] LOOP 

    SELECT INTO random_record * FROM simulated_records WHERE school = school_name ORDER BY RANDOM() LIMIT 1; 
    IF random_record.grade = '-' THEN 
     random_record.grade := 'C'; 
END IF; 
UPDATE simulated_records.grade = random_record.grade; 
END Loop; 
FOR i IN 1..num_grades[6] LOOP 

    SELECT INTO random_record * FROM simulated_records WHERE school = school_name ORDER BY RANDOM() LIMIT 1; 
    IF random_record.grade = '-' THEN 
     random_record.grade = 'D'; 

END IF; 
UPDATE simulated_records.grade = random_record.grade; 

END Loop; 

END; 
$$ 
LANGUAGE plpgsql 

Честно говоря, я просто не уверен, как правильно его обновить. Что мне делать?

Answer 1

Вам нужен пункт в ваших UPDATE команд WHERE, потому что

UPDATE simulated_records.grade = random_record.grade; 

обновляет все строки таблицы.