![]() It may be for tables with similar data within the same database or maybe you need to combine similar data from multiple databases. Sometimes, you need to combine data from multiple tables into a complete result set. Monitoring PostgreSQL with Navicat Monitor 3.Summary: in this tutorial, you will learn how to use SQLite UNION operator to combine result sets of two or more queries into a single result set.Trace Queries on your PostgreSQL Instances with Navicat Monitor 3.Viewing PostgreSQL Instance Details in Navicat Monitor 3.A Quick Guide to Naming Conventions in SQL - Part 2.A Quick Guide to Naming Conventions in SQL - Part 3.Selecting Distinct Values From a Relational Database.Implement Audit Trail Logging Using Triggers.Multi-Version Concurrency Control in PostgreSQL.A Guide to MySQL Foreign Key Constraints.The lesson here is that the multi-table UPDATE statement works best for applying mathematical operations such as incrementing and decrementing on related table columns. Today's blog presented an overview of the multi-table UPDATE statement along with an example using MySQL 8 and Navicat Premium 16. We can observe the query results in Navicat below:Īs expected, the book counts for user '1AG' and book 103 have been updated in both tables: Conclusion It causes the older values to be overwritten with the new data. Other join types like outer join and right outer join may be employed as well the only mitigating factor is that the two tables getting grouped must have a similar/matching attribute.Īs with the regular (single table) UPDATE statement, the SET keyword is used along with the UPDATE keyword to set the new values in existing rows. Meanwhile, the b.id = '1AG' condition further reduces the target rows to those which pertain to user '1AG'. In the above query, the l.id = b.book_id condition acts as an inner join which combines the two tables and operates on the combined table after checking the table constraints. Here is the query that will update both tables: Here are the definitions and contents of each table: The library Table This will avoid separate calls to the server, making it a very efficient operation. As it turns out, that's the ideal scenario to combine two separate statements into one UPDATE query. Doing so increases the count of books while decreasing the count of the books. ![]() To give the multi-table UPDATE statement a try, we'll create two tables named "library" and "book" and consider the case when one or more books are borrowed from the library. ![]() So, while the multi-table UPDATE statement is quite efficient, it is not ideal for every situation.
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