Should any right be infringed, it is totally unintentional.ĭrop me an email and I will promptly and gladly rectify it.Knex ( 'users' ). Registered trademarks of their respective companies. Software and hardware names mentioned on this site are No portion may be reproduced without my written permission. Update multiple rows (distinctive by primary key) for multiple columns in one queryĬopyright © 2023. Update multiple rows (distinctive by primary key) with different values in one queryġ2. Using MySQL REPLACE (INTO) to mimic DELETE + INSERTġ1. Combine update and insert into one statementġ0. How to create and use AUTO_INCREMENT column and use LAST_INSERT_ID functionĩ. How to do cross-table update in MySQL - Part 2Ĩ. How to do cross-table update in MySQL - Part 1ĥ. How to update top N rows of data in MySQLĤ. How to update data in a specific order in MySQLģ. We can use b.categoryid is null in the WHERE clause to identify those unmatched rows for new categories that don't exist in Categories table. Here is the update query by using left join. Here is what the result would look like for the left join before an update is run. If this does not seem to be straight forward for you, please refer to Using Outer Joins to Combine Data from Two Tables for detailed explanation about using outer joins in SELECT statement. As it uses left join, all the recordsįrom the table in the left hand side of the JOIN clause (that is the Categories_Test table) are returned in the result.Īll the matching rows in the right hand side of the JOIN clause (that is the Categories table) are also returned in the result.įor the unmatched rows, the data is returned as NULL values in Categories table. The alternative way of adding the prefix is an update with left outer join to find the new categories. Set picture = concat ( ' new- ', picture ) The most common way of adding the prefix is to do a simple update in table Categories_Test for those records whose CategoryID cannot be It's obvious that Categories_Test has two 2 records - CategoryID 9 and 10. Look at the data in table Categories shown below. The prefix we're going toĪdd is 'new-' (without the single quotes) so the picture names will be changed to below. As they are new categories, we'd like toĪdd a prefix to the filename of their pictures so that we can be easily identified as new categories. The Categories_Test table contains two more categories - Herbs/Spices and Vegetables. Our task - change data in the Picture column for records which are not in the Categories table Here is the data view after the table is populated. ( 10, ' Vegetables ', ' Plant roots, bulbs, leaf vegetables, stems, etc. ( 9, ' Herbs/Spices ', ' Herbal plants and dried spices ', ' herbs.gif ' ) , ( 8, ' Seafood ', ' Seaweed and fish ', ' seafood.gif ' ) , ( 7, ' Produce ', ' Dried fruit and bean curd ', ' produce.gif ' ) , ( 6, ' Meat/Poultry ', ' Prepared meats ', ' meat.gif ' ) , ( 5, ' Grains/Cereals ', ' Breads, crackers, pasta, and cereal ', ' cereals.gif ' ) , ( 4, ' Dairy Products ', ' Cheeses ', ' diary.gif ' ) , ( 3, ' Confections ', ' Desserts, candies, and sweet breads ', ' confections.gif ' ) , ( 2, ' Condiments ', ' Sweet and savory sauces, relishes, spreads, and seasonings ', ' condiments.gif ' ) , ( 1, ' Beverages ', ' Soft drinks, coffees, teas, beers, and ales ', ' beverages.gif ' ) , Insert into ` categories_test ` ( ` CategoryID `, ` CategoryName `, ` Description `, ` Picture ` )
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