Tag: how to

How to Create a Computed Column in SQLite

Posted on by Ian

Generated column support was added to SQLite in version 3.31.0, which was released on 22 January 2020.

Generated columns and computed columns are the same thing. They are columns whose values are a function of other columns in the same row.

In SQLite, generated columns are created using the GENERATED ALWAYS column-constraint when creating or altering the table.

There are two types of generated column; STORED and VIRTUAL. Only VIRTUAL columns can be added when altering a table. Both types can be added when creating a table.

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Convert NULL Values to the Column’s Default Value when Inserting Data in SQLite

Posted on by Ian

One of SQLite‘s non-standard extensions to SQL is the ON CONFLICT clause.

This clause allows you to determine what should happen when certain conflicts occur due to a constraint violation.

One of the things you can use this clause for is to replace NULL values with a column’s default value when inserting or updating data in a table.

By default, if you try to explicitly insert NULL into a column with a NOT NULL constraint, it will fail.

And if you try to explicitly insert NULL into a column without a NOT NULL constraint, then NULL will be assigned to that column, even if there’s a DEFAULT clause.

However, you can use the ON CONFLICT clause to set it to the default value instead of NULL.

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How to Skip Rows that Violate Constraints When Inserting Data in SQLite

Posted on by Ian

In SQLite, when you try to insert multiple rows into a table, and any of those rows violates a constraint on that table, the operation will fail.

This is to be expected, after all, that’s what the constraint is for.

But what if you just want to ignore any rows that violate constraints? In other words, if a row violates a constraint, you want SQLite to skip that row, then carry on processing the next row, and so on.

Fortunately, there’s an easy way to do this in SQLite.

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