python sqlite3.connect-无法打开数据库文件

我在Mac上运行Python3，以测试简单的sql数据库。我有以下代码

import sqlite3

# connecting to the database
connection = sqlite3.connect("myTable.db")
crsr = connection.cursor()

# SQL command to create a table in the database
sql_command = """CREATE TABLE emp (
staff_number INTEGER PRIMARY KEY,
fname VARCHAR(20),
lname VARCHAR(30),
gender CHAR(1),
joining DATE);"""

# execute the statement
crsr.execute(sql_command)

# SQL command to insert the data in the table
sql_command = """INSERT INTO emp VALUES (23, "Rishabh", "Bansal", "M", "2014-03-28");"""
crsr.execute(sql_command)

crsr.execute(sql_command)
connection.commit()
connection.close()

运行此代码时，出现错误：

Traceback (most recent call last):
  File "test.py", line 8, in <module>
    connection = sqlite3.connect("myTable.db")
sqlite3.OperationalError: unable to open database file

我想念什么？我试图取代("myTable.db")以(".myTable.db")和("./myTable.db")，但同样的问题。请提出建议。