cx_Oracle 'SELECT INTO' 绑定变量问题 - ORA-01036：非法变量名称/编号

Question

我收到以下代码的“非法变量名”错误。一个是 out 参数，不确定此语法是否适用于 out 参数，但也尝试了一些变体，包括使用 :1, :2 语法传递值元组 - 这也不起作用。

def no_snapshot_for_day(timestamp):
    # Do we have a snaphot already today
    no_snapshot = True
    snapshot_count = cursor_analytics.var(cx_Oracle.NUMBER)

    sql = "SELECT COUNT(1) INTO :v1 FROM PYTHON_SNAPSHOT WHERE SNAPSHOT_DATE=trunc(:v2) AND SNAPSHOT_STATUS='OK'"

    cursor_analytics.execute(sql,{"v1":snapshot_count, "v2":timestamp})


    if snapshot_count.getvalue() > 0:
        no_snapshot = False

    return no_snapshot

Answer 1

'select into' 是一种 PL/SQL SQL 语法。从技术上讲，您可以执行

sql = "BEGIN SELECT COUNT(1) INTO :v1 FROM PYTHON_SNAPSHOT WHERE SNAPSHOT_DATE=trunc(:v2) AND SNAPSHOT_STATUS='OK'; END;"

但在实践中，只需执行“选择”，然后获取数据，类似于以下（未经测试的）代码：

with connection.cursor() as cursor_analytics:
    sql = "SELECT COUNT(1) as snapshot_count FROM PYTHON_SNAPSHOT WHERE SNAPSHOT_DATE=trunc(:v2) AND SNAPSHOT_STATUS='OK'"
    cursor_analytics.execute(sql,{"V2": timestamp})
    (snapshot_count,) = cursor_analytics.fetchone()
    print(snapshot_count)