Because this column is declared as INTEGER PRIMARY KEY, it will not accept NULL values. In this example, the supplier_id is the PRIMARY KEY column of the suppliers table. The following example creates a new table named suppliers: CREATE TABLE suppliers( Once a NOT NULL constraint is attached to a column, any attempt to set the column value to NULL such as inserting or updating will cause a constraint violation. ![]() Therefore, it has been decided to allow NULL values in the PRIMARY KEY column. If this bug is fixed to conform with the SQL standard, then it might break the legacy systems. This is due to a bug in some early versions. However, SQLite allows NULL values in the PRIMARY KEY column except that a column is INTEGER PRIMARY KEY column or the table is a WITHOUT ROWID table or the column is defined as a NOT NULL column. Unlike other constraints such as PRIMARY KEY and CHECK, you can only define NOT NULL constraints at the column level, not the table level.īased on the SQL standard, PRIMARY KEY should always imply NOT NULL. To define a NOT NULL constraint for a column, you use the following syntax: CREATE TABLE table_name (Ĭode language: SQL (Structured Query Language) ( sql ) By default, all columns in a table accept NULL values except you explicitly use NOT NULL constraints. When you create a table, you can specify whether a column accepts NULL values or not. ![]() Introduction to SQLite NOT NULL constraint Summary: in this tutorial, you will learn how to use the SQLite NOT NULL constraint to ensure the values in a column are not NULL.
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