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This feature was introduced to prevent people inadvertently updating or deleting more rows in a table than they planned on. At every site we’ve worked at, every now and then someone will accidentally update or delete all the rows in a critical production table. Enabling the Safe Update Mode feature helps to prevent this.
When this feature is enabled, AQT will check the number of rows affected by every Update or Delete statement you run. If this is greater than the value you specify for When more than x Rows Changed then:
By default the row-limit is set to 1, so any update affecting more than one row will have these actions happen. You can set this to a higher value if you are running a series of updates that you know are going to affect multiple rows, however we recommend that you do not switch this feature off - instead, you should increase the row-limit.
From a technical point of view, this feature is achieved by doing a Start Transaction before any update, then a commit / rollback, End Transaction after. Some databases (such as MS Access) occasionally have trouble with Transactions and give errors such as “Option not valid at this time”. If this happens you will need to switch off Safe Update Mode.
This option is not available in a number of circumstances:
By default, these settings are not remembered between sessions - eg. if you switch off Safe Update Mode, when you start AQT the next time it will be set on. The reason for this is that Safe Update Mode is a safety mechanism and we wish to prevent people switching it off permanently by mistake. However if you really want to switch it off permanently, click Remember Between Sessions.