Best practices for updating data base
So, we can create a query with the following update statement: UPDATE “Employees”, SET, and then assign the value of the string “Stella” to the “first name” column, the string “Parkinson” to the “last name” column, the 31 of December 1990 to “birth date”, and “F” to “gender”.The condition here is to have an employee number that equals John Smith’s number, 999901.After that moment, even if you run the ROLLBACK clause 20 times, you can get to the state of only the last COMMIT.You cannot restore data to a state corresponding to an earlier COMMIT.On the left-hand side of the window that pops up, choose the “SQL Editor” section.On the right-hand side, scroll down to get to the box that says, “Safe Updates”.It will refer to the state corresponding to the time you executed COMMIT.This means if you have already used COMMIT 10 times, ROLLBACK will have an effect on the last execution you have performed.
So, let’s exit this connection and then reconnect, typing the password once again! In the previous post about SQL INSERT Statement, we inserted an employee under the number of 9-9-9-9-0-1, remember? The syntax to adhere to is UPDATE table name, the keyword SET, column names and the respective values assigned to them, and finally – WHERE, and a certain condition, or set of conditions, that must be satisfied.
Remember, you should be careful when using this command because once you execute COMMIT, you cannot reverse any change!
So, after running ROLLBACK, where will we go back to? We see the information we had in the “Departments Duplicate” table at the beginning of this post.
Nevertheless, nothing would have happened – the statement would have worked, affecting 0 rows, because the data table doesn’t contain an employee with such a number at the moment of the query’s execution.
Stay focused for another interesting feature we will discuss next.