提示输入变量值时恢复扫描状态

Question

如何检测当前SCAN 状态并在更改后恢复？

相关脚本的摘录：

SET SCAN OFF
SET ECHO ON
SET SQLBLANKLINES ON

SET SCAN ON
UPDATE TABLE_NAME SET CREATED_BY = &&created_by;
SET SCAN OFF

问题是如果脚本没有第一行（SET SCAN OFF），那么提示用户的代码不应该在之后关闭SCAN 状态。伪代码解决方案：

-- The next line might not exist, or be "SET SCAN ON".
SET SCAN OFF
SET ECHO ON
SET SQLBLANKLINES ON

-- Remember if the scanning was on or off.
PUSH SCAN STATE
SET SCAN ON
UPDATE TABLE_NAME SET CREATED_BY = &&created_by;

-- Revert scanning to its former state.
POP SCAN STATE

PUSH SCAN STATE 行会记住状态，因此如果通过删除第一行来更改代码，由于对应的POP SCAN STATE，脚本的其余部分仍可按预期工作。

Answer 1

sqlplus STORE 命令应该这样做，不幸的是它似乎没有保存SCAN 状态（SQLPlus 9.2.0.1.0）。我将用另一种设置进行演示（TIMING）：

SQL> show timing
timing OFF
SQL> -- save parameters into an os file
SQL> store set param.sql create
Created file param.sql
SQL> -- run script
SQL> SET TIMING ON
SQL> show timing
timing ON
SQL> -- reset state
SQL> @param.sql
SQL> show timing
timing OFF