Sql query for each row update

Thanks to the SQL Server relational database management system tables, …. January 13, Facebook Twitter Youtube. Example insert update.

SQL Server Errors. Useful SQL. Why do you need to store this rank? All it does is require you to maintain it every time the table is touched. Can't you calculate this number at query time? Add a comment. Active Oldest Votes. RowId from Renewals as r left join Renewals as p on p. AccountId and p. RowId , r.

RowId from cte as r left join cte as p on p. Improve this answer. SqlZim SqlZim 2, 1 1 gold badge 9 9 silver badges 22 22 bronze badges. Everything but the quirky update ; — Erik Darling. How do I attach an excel file so you can see what the actual output needs to be? Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. In SQL how do you update each row of the table by finding all rows that are equal for a column, then set another column equal to eachother Ask Question.

Asked 8 years ago. Active 1 year ago. Viewed 39k times. So basically this would be the psuedo code, but I don't know how to do this in SQL, please help. Improve this question. Start thinking in sets and do not loop through each row in a table.

Basically what happened is we converted a sequence column to use guids so there should be no duplicates — hthomos. Add a comment. Your first or third options are the best way to go. For either of them, you want an index on table1 id. In general, it is better to run one query rather than multiple queries because the overhead of passing data in and out of the database adds up.

In addition, each update starts a transactions and commits it -- more overhead. That said, this will probably not be important unless you are updating thousands of records. The overhead is measured in hundreds of microseconds or milliseconds, on a typical system. Probably the best thing to do is to make a prepared statement with a placeholder then loop through your data executing the statement for each value. Then the statement stays in the database engine's memory and it quickly just executes it with the new value each time you call it rather than start from scratch.

I came upon this post when trying to solve a very similar problem so thought I'd share what I found. My answer uses the case keyword, and applies to when you are trying to run an update for a list of key-value pairs not when you are trying to update a bunch of rows to a single value.

You can do something like this:. How are we doing? Please help us improve Stack Overflow. Take our short survey. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more.

Ask Question. Asked 6 years, 2 months ago.