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It is important to maintain the history of the prices of the products.
We can create a trigger to update the 'product_price_history' table when the price of the product is updated in the 'product' table.
That’s a terrible way to update data, but for various reasons, I’m sure many readers have found themselves in a similar situation.
It happens a lot when I’m working with a client who has multiple versions of data in different spreadsheets, and I’m tasked with tidying it all up, standardizing formatting and importing it into a relational database.
In this article I’ll give an overview of each feature, help you understand how to choose among them, and point out some things to watch out for. I assume My ISAM tables without support for transactions, with the following sample data: create table t1 ( a int not null primary key, b int not null, c int not null ) type=My ISAM; create table t2 ( d int not null primary key, e int not null, f int not null ) type=My ISAM; insert into t1 (a, b, c) values (1, 2, 3), (2, 4, 6), (3, 6, 9); insert into t2 (d, e, f) values (1, 1, 1), (4, 4, 4), (5, 5, 5);.There are two types of triggers based on the which level it is triggered.1) Row level trigger - An event is triggered for each row upated, inserted or deleted.1) Create the 'product' table and 'product_price_history' table Once the above update query is executed, the trigger fires and updates the 'product_price_history' table.4)If you ROLLBACK the transaction before committing to the database, the data inserted to the table is also rolled back.