How to declare pre-computed columns on mysql?

by muriel.schmidt , in category: MySQL , a month ago

How to declare pre-computed columns on mysql?

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1 answer

by scotty_walker , a month ago

@muriel.schmidt 

To declare pre-computed columns in MySQL, you would typically use a generated column. Generated columns allow you to define a virtual column based on an expression, which can include calculations or concatenations of other columns.


Here is an example of how to declare a pre-computed column in MySQL:

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CREATE TABLE example_table (
    id INT PRIMARY KEY,
    column1 INT,
    column2 INT,
    precomputed_column INT AS (column1 + column2) STORED
);


In this example, we are creating a table with an id column and two other columns, column1 and column2. We then declare a precomputed_column that calculates the sum of column1 and column2 and stores the result in the table as a stored generated column.


You can modify the expression used in the generated column to perform different calculations or transformations on the data. Generated columns can be either STORED or VIRTUAL, with STORED columns storing the result in the table, while VIRTUAL columns calculate the result on-the-fly whenever the column is queried.