Suppose the employee id 192 Sarah Bell changed her last name from Bell to Lopez and we need to update her record in the employees table.
When I try to update only the missing data the non-matched data is also updated but to NULL. The reason some of your rows are getting NULLs updated is due to the subquery.A co-worker recently asked me why she would get timeout when updating a column in a big table. If the large table has constraints and indexes, make sure that you have the scripts to re-create them. Rename the temporary table to the name of the actual table. Notice that this setting differs from the setting in the Execution time-out box in SQL Server Management Studio.This column will be updated to 0 (zero) because a default value of 0 (zero) constrain is now added to the table. Although I didn’t ask the exact size in MB, I am pretty sure that a table with over 40 million records is not a small table anymore. Create a temporary table with the same table schema. Copy all the data from the actual table to the temporary table using INSERT … Make sure that the column that needs to be updated to 0 (zero) has value 0 (zero) in the SELECT clause. By default, the setting in the Execution time-out box for Query Editor in SQL Server Management Studio is zero.I had a blog a few weeks ago that talked about 4 different scenarios when deleting or updating data on a large table. Therefore, Query Editor waits infinitely for the query to finish and never times out.SQL #50–Deleting or updating data from a table of 20 GB I didn’t refer my co-worker to the above blog because the blog is really too long to read in one minute and many scenarios are not applicable to the issue.