Collections:
Use Existing Column Values in the SET Clause in MySQL
How To Use Existing Column Values in the SET Clause in MySQL?
✍: FYIcenter.com
If a row matches the WHERE clause in a UPDATE statement, existing values in this row can be used in expressions to provide new values in the SET clause. Existing values are represented by column names in the expressions. The tutorial exercise below shows a good example:
mysql> UPDATE fyi_links SET id = id+200, counts = id*2 WHERE id >= 500; Query OK, 5 rows affected (0.01 sec) Rows matched: 5 Changed: 5 Warnings: 0 mysql> SELECT id, url, notes, counts, DATE(created) FROM fyi_links WHERE id >= 500; +-----+-------------------+-------+--------+---------------+ | id | url | notes | counts | DATE(created) | +-----+-------------------+-------+--------+---------------+ | 801 | moc.retneciyf.ved | Wrong | 1602 | 2006-04-30 | | 802 | moc.retneciyf.abd | Wrong | 1604 | 2006-08-31 | | 803 | moc.retneciyf.aqs | Wrong | 1606 | 2006-08-31 | | 810 | | Wrong | 1620 | 2006-08-31 | | 700 | moc.retneciyf.www | Wrong | 1400 | 2006-08-31 | +-----+-------------------+-------+--------+---------------+ 5 rows in set (0.00 sec)
This statement increased values in the id column by 200. It also updated the counts column with the newly increased id value.
⇒ Order of Columns in the SET Clause in MySQL
⇐ Update Column Values on Multiple Rows in MySQL
2018-01-13, 1938🔥, 0💬
Popular Posts:
Why I Can Not Enter 0.001 Second in DATETIME values in SQL Server Transact-SQL? If you enter millise...
How To Drop a Stored Procedure in Oracle? If there is an existing stored procedure and you don't wan...
How To Break Query Output into Pages in MySQL? If you have a query that returns hundreds of rows, an...
How To Convert Numeric Expression Data Types using the CAST() Function in SQL Server Transact-SQL? I...
How To Convert a Unicode Strings to Non-Unicode Strings in SQL Server Transact-SQL? Since Unicode ch...