mysql 如何遍历集合

SELECT * FROM table_name;

import mysql.connector

db = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="yourdatabase"
)

cursor = db.cursor()

cursor.execute("SELECT * FROM table_name")

for row in cursor:
  print(row)

DECLARE cur CURSOR FOR SELECT * FROM table_name;
OPEN cur;
FETCH NEXT FROM cur INTO @var1, @var2, ...;
WHILE @@FETCH_STATUS = 0
BEGIN
  -- 处理每一行数据
  FETCH NEXT FROM cur INTO @var1, @var2, ...;
END;
CLOSE cur;
DEALLOCATE cur;

DELIMITER //

CREATE PROCEDURE TraverseSet()
BEGIN
  DECLARE done INT DEFAULT FALSE;
  DECLARE var1 datatype;
  DECLARE var2 datatype;
  -- 声明其他需要的变量

  DECLARE cur CURSOR FOR SELECT column1, column2 FROM table_name;
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

  OPEN cur;

  read_loop: LOOP
    FETCH cur INTO var1, var2;
    IF done THEN
      LEAVE read_loop;
    END IF;
    -- 处理每一行数据
  END LOOP;

  CLOSE cur;
END //

DELIMITER ;

CALL TraverseSet();