MySQL更改数据字段的前几位数字的方法示例

UPDATE table_name
SET column_name = CONCAT('new_prefix', SUBSTRING(column_name, length_of_prefix + 1))
WHERE condition;

UPDATE customers
SET phone_number = CONCAT('456', SUBSTRING(phone_number, 4))
WHERE phone_number LIKE '123%';

UPDATE table_name
SET column_name = CONCAT('new_prefix', SUBSTRING(column_name, length_of_prefix + 1))
WHERE condition;

UPDATE employees
SET id_number = CONCAT('654321', SUBSTRING(id_number, 7))
WHERE id_number LIKE '123456%';

UPDATE table_name
SET column_name = CONCAT('new_prefix', SUBSTRING(column_name, length_of_prefix + 1))
WHERE condition;

UPDATE addresses
SET postal_code = CONCAT('98', SUBSTRING(postal_code, 3))
WHERE LENGTH(postal_code) >= 2;

UPDATE table_name
SET column_name = REGEXP_REPLACE(column_name, 'pattern', 'replacement')
WHERE condition;

UPDATE orders
SET order_id = REGEXP_REPLACE(order_id, '^1234', '5678')
WHERE order_id REGEXP '^1234';

UPDATE table_name
SET column_name = 
  CASE
    WHEN condition_1 THEN new_value_1
    WHEN condition_2 THEN new_value_2
    ...
    ELSE column_name
  END
WHERE condition;

UPDATE products
SET product_code = 
  CASE
    WHEN category = 'A' THEN CONCAT('111', SUBSTRING(product_code, 4))
    WHEN category = 'B' THEN CONCAT('222', SUBSTRING(product_code, 4))
    ELSE product_code
  END
WHERE LENGTH(product_code) >= 3;

UPDATE orders
SET order_number = order_number + 10
WHERE order_number >= 1000 AND order_number < 2000;

DELIMITER //
CREATE FUNCTION modify_grade(original_grade VARCHAR(10))
RETURNS VARCHAR(10)
BEGIN
    DECLARE school_code VARCHAR(2);
    SET school_code = 'AB'; -- 假设学校代码为'AB'
    RETURN CONCAT(school_code, SUBSTRING(original_grade, 3));
END //
DELIMITER ;

UPDATE students
SET grade = modify_grade(grade)
WHERE ...; -- 添加适当的条件