Updating a field in sql
The following UPDATE statement edits both columns at one time but still limits it to one customer: UPDATE Customer SET first_name = ‘Tom', last_name = ‘Smith' WHERE Customer Id = 123 The following two tables show you a before and after snapshot of your data when you run the SQL UPDATE statement: Before When you want to edit more than one column, you just append a comma to the end of the column section of the statement and add your column with a new value. If you recall from Lesson 2, NULL values are used when nothing is entered by the user or no value exists.
The user could have accidentally entered a typo or he didn't enter any information and you later ask him for it in the future.
You could use a SELECT statement in your UPDATE statement to edit your data.
The following SQL query is an example: UPDATE Customer SET city = ‘Miami' WHERE Customer Id IN (SELECT Id FROM External Table) Here is an example of the External Table: Notice that the first table does not have all the data as the second.
The following code is an UPDATE statement template: UPDATE One issue with the above statement – the statement has no WHERE clause. However, if you don't insert a WHERE clause in your UPDATE statements, you will change every record in the database.
Typically, you want to change a subset of records in your tables and not all records.