Category: SQLite

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 ON CONFLICT Works in SQLite

Posted on by Ian

SQLite has the ON CONFLICT clause that allows you to specify how to handle constraint conflicts. It applies to UNIQUE, NOT NULL, CHECK, and PRIMARY KEY constraints (but not FOREIGN KEY constraints).

There are five possible options you can use with this clause:

  • ABORT
  • FAIL
  • IGNORE
  • REPLACE
  • ROLLBACK

This article provides examples and an explanation of each of these options.

The ON CONFLICT clause is used in CREATE TABLE statements, but it can also be used when inserting or updating data by replacing ON CONFLICT with OR.

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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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