Updating a select statement to update
Pinal is also a Cross Fit Level 1 Trainer (CF-L1) and Cross Fit Level 2 Trainer (CF-L2).I'm trying to update a column in SQL Server 2016 using CASE statement because I have to change the value based on different conditions.If it does, then only one of the join rows will be used to update the target row, but which one will be used is not readily predictable.Because of this indeterminacy, referencing other tables only within sub-selects is safer, though often harder to read and slower than using a join.  Set the value of column C1 in table T to 1, only in those rows where the value of column C2 is "a".An email from an old college friend landed my mailbox about UPDATE FROM SELECT Statement with Condition:“Hey Pinal,”I have two tables. The requirement was to update Item Price table column Price with US price and for that it required to divide the column by 60.I want to conditionally update data in one table based on another table. I have included sample scripts and an image for further explanation. ”It always delights to receive email from an old college friend and particularly it is even more interesting when they have a question w where I can help. Here is the sample script of the table displayed in the image.See CREATE TABLE statement for details about updating IDENTITY/AUTOINCREMENT columns, which are another type of DEFAULT column. The SQL UPDATE Query is used to modify the existing records in a table.
In some databases, such as Postgre SQL, when a FROM clause is present, what essentially happens is that the target table is joined to the tables mentioned in the fromlist, and each output row of the join represents an update operation for the target table.Along with 16 years of hands on experience he holds a Masters of Science degree and a number of database certifications.For any SQL Server Performance Tuning Issue send an email at [email protected] using FROM, one should ensure that the join produces at most one output row for each row to be modified.In other words, a target row shouldn't join to more than one row from the other table(s).