下列聚合函数中不忽略空值null的是_MYSQL源代码的特性是( )和稳定性

#!/usr/bin/python3
import pymysql
import zlib
"""
-- dll record log
CREATE TABLE ddl_execute_record
(
    id                     INT AUTO_INCREMENT PRIMARY KEY,
    db_name                 VARCHAR(50),
    ddl_statement         LONGTEXT,
    ddl_hash                BIGINT,
    execute_status     TINYINT COMMENT "0:init;1:successful;-1:fail",
    create_datetime     DATETIME(6),
    last_update            DATETIME(6)
);
"""

class mysql_release(object):
    def __init__(self):
        return

    def __init__(self, host=None, port=None,user=None,password=None,db=None,charset=None):
        self.host = host
        self.port = port
        self.user = user
        self.password = password
        self.db = db
        self.charset = charset

    def get_conn(self):
        if not self.db:
            raise(NameError,"no database info")
        conn = pymysql.connect(host=self.host,  port=self.port,  user=self.user,password=self.password, db=self.db, charset=self.charset)
        if not conn:
            raise(NameError,"conn database fail")
        else:
            return conn

    def execute_noquery(self,str_sql):
        try:
            conn = self.get_conn()
            cursor =conn.cursor()
            cursor.execute(str_sql)
            last_rowid = cursor.lastrowid
            conn.commit()
        except  Exception as err:
            raise
        return last_rowid

    def execute_query(self,str_sql):
        list = None
        try:
            conn = self.get_conn()
            cursor =conn.cursor()
            cursor.execute(str_sql)
            list = cursor.fetchall()
        except  Exception as err:
            print(err)
        return list

    def execute_statement(self,sql_statement):
        #尼玛这个hash不好使，忽略先，与内存地址有关，这里目的是对sql语句的字符串进行固定hash运算，然后基于hash值作比较
        ddl_hash = hash(sql_statement)
        ddl_log_search = """select * from db_release_audit.ddl_execute_record where ddl_statement = "{0}" and execute_status=1 """.format(sql_statement.strip())
        ddl_log_insert = """insert into db_release_audit.ddl_execute_record(db_name,ddl_statement,ddl_hash,execute_status,create_datetime,last_update) 
                    values ("{0}","{1}",{2},{3},now(6),now(6))""".format("master",sql_statement.strip(),ddl_hash,0)
        ddl_log = self.execute_query(ddl_log_search)
        if not ddl_log:
            last_rowid = self.execute_noquery(ddl_log_insert)
            if last_rowid:
                update_statment = ""
                try:
                    self.execute_noquery(sql_statement)
                    # update sql statement execute successful
                    update_statment = """update db_release_audit.ddl_execute_record set execute_status = 1,last_update = now(6) where id = {0}""".format(last_rowid)
                except Exception as err:
                    # update sql statement execute fail
                    update_statment = """update db_release_audit.ddl_execute_record set execute_status = -1,last_update = now(6) where id = {0}""".format(last_rowid)
                    print(err)
                finally:
                    self.execute_noquery(update_statment)
            else:
                print("record log fail")
        else:
            print("the statment executed info: "+str(ddl_log[0]))


if __name__ == "__main__":
    dict_conn = {"host": "***。***。***。***", "port": 3306, "user": "root", "password": "***", "db": "***", "charset":"utf8mb4"}
    # parse db name and sql statement from sql file or anywhere
    db_name = "user_database_name"
    sql_statement = """ 
    create table t_1 (id int primary key);
    """
    release_obj = mysql_release(host=dict_conn["host"], port=dict_conn["port"], user=dict_conn["user"],password=dict_conn["password"], db=dict_conn["db"], charset=dict_conn["charset"])
    try:
        release_obj.execute_statement(sql_statement)
    except Exception as err:
        print(err)
        raise

代码100分