Updating a table from another table
The general form to use is: contains the update values; we use joins to do the matching.
Let suppose that someone has accidentally updated all esql Sales Person. How can we easily repopulate this data without having to retype it in?
The value is changed to ‘Kris ‘You can handle errors when executing an UPDATE statement using a TRY…CATCH construct.
There are several common reason an UPDATE statement may fail.
If 'N' is not specified, SQL Server converts the string to the code page that corresponds to the default collation of the database or column.
Any characters not found in this code page are lost.
Some of the common ones are: In these cases, the UPDATE statement execution stops and the UPDATE generates an error.
For instance, if a field is defined as CHAR(10) and you update the value ‘Kris’ into this column, then it will be padded with six spaces.
In the diagram below you’ll see where there is a match between these two tables: By matching esql Sales Person. Notice here we’re constructing a full name from the views First Name and Last Name columns. So, once we have the join, the last bit of business to it do the update. Suppose the Sales Last Year figures were found to be incorrect and needed to be adjusted by five percent.
Full Name to v Sales Person we can update esql Sales Person. Before we go much further, let’s first wipe out the city column values. You can easily adjust the values using the following statement: However, suppose the sales department want a record of all changes.
Knowing that esql Sales Person was originally populated by information from Sales we use knowledge to set up a query that pumps data from v Sales Person into esql Sales Person.
This is possible since the sales person’s full name is common to both tables. The OUTPUT clause is used to log changes made to rows affect by an UPDATE statement.The UPDATE statement is complex and there are many elements to consider. For a full list check out the UPDATE (Transact-SQL) article.