MySQL Update and delete

Update and delete operations The SQL statement is relatively simple, but note that when using update, pay attention to the Weher condition limit, the following statement is to update only the email address of ID 10005, if not with the WHERE statement limit, then the table all the email update to [ Email protected]:

Delete the value of a column, set to NULL.

Delete the row's SQL statement, using Delete, and delete the same where you want to delete the row, if not specified, deletes all rows in the table.

DELETE from Customers

WHERE cust_id = 10005;

At this point, we also see the importance of the primary key in a table. In addition, before update and delete, you can use the SELECT statement to test whether the condition qualified by the where statement is correct.