使用 Python ibm_db 包将时间戳更新为 DB2 中的当前时间戳

Question

每次我的脚本部分运行时，我都会尝试将 db2 中的 lastupdated 时间戳设置为当前时间戳

datetimes = datetime.now()
datetime1 = datetimes.strftime("%Y-%m-%d  %H:%M:%S")
datetime2 = datetime.strptime(datetime1,'%Y-%m-%d  %H:%M:%S')
print(type(datetime2))
print(datetime2)
sql = "update salesorder set LASTUPDATEUSER = 'Testing' and LASTUPDATEDATETIME = ? where code ='0888' "
prepared = ibm_db.prepare(conn, sql)
returnCode = ibm_db.bind_param(prepared,1,datetime2, ibm_db.SQL_PARAM_INPUT,ibm_db.SQL_CHAR)

if returnCode == False:
    print("unable to bind")
#ibm_db.execute(upstmt)
#param = param1
returnCode = ibm_db.execute(prepared)

if returnCode == False:
    print("unable to execut")

运行此脚本时出现错误

Traceback (most recent call last):
  File "new.py", line 27, in <module>
    returnCode = ibm_db.execute(prepared)
 SQLCODE=-420atement Execute Failed: [IBM][CLI Driver][DB2/LINUXX8664] SQL0420N  Invalid character found in a character string argument of the function "BOOLEAN".  SQLSTATE=22018

我尝试了多种解决方案，例如将日期时间作为字符串传递，但没有解决问题，这是 db2 '2020-02-21 13:37:37' 中使用的时间戳格式

如果有人可以请提供一种解决此问题的方法，这将非常有帮助

Answer 1

您的更新 stmt 错误。变化：

update salesorder 
    set LASTUPDATEUSER = 'Testing' and LASTUPDATEDATETIME = ? 
where code ='0888'

到：

update salesorder 
    set LASTUPDATEUSER = 'Testing'
      , LASTUPDATEDATETIME = ? 
where code ='0888'

或：

update salesorder 
    set (LASTUPDATEUSER, LASTUPDATEDATETIME) = ('Testing', ?) 
where code ='0888'

您收到的错误消息令人费解，但这是由于您尝试从字符串中评估布尔值：

db2 "values 'testing' and current_timestamp = current_timestamp"

1 
--
SQL0420N  Invalid character found in a character string argument of the 
function "BOOLEAN".  SQLSTATE=22018

比较

db2 "values true and current_timestamp = current_timestamp"

1 
--
 1

即使成功，您在尝试为时间戳列分配布尔值时也会出错。

我猜旧版本的 Db2 在准备期间会反对，但现在类型检查要宽松得多，这会不时导致非常反直觉的错误消息

也就是说，您可能想研究一下：

update salesorder 
    set (LASTUPDATEUSER, LASTUPDATEDATETIME) = ('Testing', current_timestamp) 
where code ='0888'

然后您的代码将简化为：

sql = """update salesorder 
        set (LASTUPDATEUSER, LASTUPDATEDATETIME) = ('Testing', current_timestamp) 
    where code ='0888'"""
prepared = ibm_db.prepare(conn, sql)
returnCode = ibm_db.execute(prepared)

if returnCode == False:
    print("unable to execut")

作为一个侧节点，我觉得显式绑定参数有点麻烦，通常只是这样做：

ibm_db.execute(prepared, (param1, ...))

如果目的只是在行更改时更新时间戳，请考虑触发器：

create trigger trg1 
no cascade before update on salesorder 
referencing new as n 
for each row 
    set n.LASTUPDATEDATETIME = current_timestamp

如果您将更新语句更改为：

update salesorder 
    set LASTUPDATEUSER = 'Testing' 
where code ='0888'

触发器会为你做到这一点：

db2 "select * from salesorder"

LASTUPDATEUSER       LASTUPDATEDATETIME         CODE 
-------------------- -------------------------- -----
Testing              2020-04-11-11.51.22.055602 0888 

  1 record(s) selected.

./aa.py

db2 "select * from salesorder"

LASTUPDATEUSER       LASTUPDATEDATETIME         CODE 
-------------------- -------------------------- -----
Testing              2020-04-11-11.58.50.222753 0888 

  1 record(s) selected.

根据您的 Db2 版本，您还可以考虑将列声明为：

FOR EACH ROW ON UPDATE AS ROW CHANGE TIMESTAMP

您可能希望始终生成，但我认为您无法将列更改为该列，因此您必须做更多的工作才能将其落实到位。