![]() Works with: MySQL (not PostgreSQL, SQL Server, Oracle) The difference is that the table to be updated is not mentioned in the FROM clause. WHERE person.person_id = account.person_id ![]() SET account_number = account.account_number This is a variation on the Update with Join method above that works with PostgreSQL. Works with: PostgreSQL, SQL Server (not MySQL, Oracle) Notice that there is only one table in the UPDATE clause (the “p” table) and there are the two tables in the From clause. The data is matched on the person_id field as mentioned in the Join clause. ![]() This query will update the account_number in the person table to the account_number in the account table. It’s similar to other statements like Select and allows you to retrieve the value from one table and use it as a value to update in another table. This version of the Update statement uses a Join in the FROM clause. Works with: SQL Server (not MySQL, Oracle, PostgreSQL) Our examples in this guide will show you how to update the person.account_number field based on the related account.account_number field. We can see that the account_number field in the person table is NULL. Here’s what the sample data looks like when we select from it. INSERT INTO account (account_id, account_number, person_id) VALUES INSERT INTO person (person_id, first_name) VALUES INSERT INTO account (account_id, account_number, person_id) INSERT INTO person (person_id, first_name) The sample code is similar for each database, but the data types are different.ĭownload the SQL file with this sample data and all of the Update methods on my GitHub repository here. Here are our SQL statements to create the tables. account: stores account details that are created for people.person: stores information about people that are in the system.We’ll prepare some sample data to use in our examples. Some methods may be much faster than others, as they depend on your tables and the quantity of data. The methods to do this are different between Oracle, SQL Server, MySQL, and PostgreSQL.Īlso, you may want to test the performance of each of these “SQL update from select” methods. Or you may have loaded data from an external source into one table, and want to get some of this data into your “main tables”. We may have a column in one table but the values for that are derived or calculated from data in another table. Why would we want to include a second table? The problem with the simple UPDATE statement is that it can only take a single table. I’ve written about this in my guide to the SQL Update statement. You can also specify a condition in the WHERE clause so that only matching rows are updated. You can specify one table and one or more pairs of columns and values. The syntax of an update statement is this: UPDATE table To update data in a table, we can run an UPDATE statement.
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