1.1 The update query below shows that the Picture column is updated by looking up the same ID value in Category ID column in table Categories_Test and Categories.
The join condition is specified in the WHERE clause.
The subquery should return only one row for each row in the update table that matches the WHERE clause.
The tutorial exercise below shows you a good example: Note that if column names are confusing between the inner table and the outer table, you need to prefix column names with table names, like "fyi_= fyi_links.id".
What I want to do is either insert only the new rows, or insert the new rows and update the changed rows (depending on the scenario). If I want to insert only the rows that will not violate the unique index, I can: Which method to use largely depends on requirements.
I have to start with one spreadsheet, then insert and/or update the differences from the others.If performance is the goal and the queries don’t need to be portable, I see no reason not to use the solution that performs best.If the software must support multiple database backends performance is critical, there’s probably no way to avoid writing different queries for each supported backend.2.1 When updating multiple columns, use comma to separate each column after the SET keyword.In Categories_test table, both Description and Picture column were updated for 8 records.My SQL Tutorials My SQL Tutorial - UPDATE Using Data from Other Tables By: (Continued from previous topic...) How To Use Values from Other Tables in UPDATE Statements?If you want to update values in one table with values from another table, you can use a subquery as an expression in the SET clause.In this tutorial, we are going to look at four scenarios for My SQL cross table update.Suppose we have two tables Categories and Categories_Test. The common column in the two tables is Category ID.Cross table update in My SQL (also known as correlated update, or multiple table update) refers to the operation that updates records in one table based on whether they match or don't match records in another table.The matching uses the concept explained in the JOIN operation that we discussed in this section - Querying Multiple Tables.