Doubles are stored as 8-byte IEEE, text in the format configured for the database file (UTF-8 by default), and BLOBs are unmodified. On disk, SQLite uses a compact format for integers, depending on their actual value. Column Affinity Behavior JavaScript Example. This section comprises the following: SQLite characteristics. Sqlite doesn't give you access to the underlying data type, you acess the data through functions like sqlite_column_int, and if the stored data is of a diffent type, it's converted to the requested type. SQLite is a database engine packaged along with the native sdk. You can query the actual type of the value stored using sqlite3_column_type. Yes, your INTEGER affinity column can contain strings. the string is "Hello!"), it is inserted as a string. The type affinity of a column is the recommended type for data stored in that column. if you insert a string into a column with INTEGER affinity, it tries to convert that string to an integer. In order to maximize compatibility between SQLite and other database engines, and so that the example above will work on SQLite as it does on other SQL database engines, SQLite supports the concept of 'type affinity' on columns. When you insert a value into a column, SQLite tries to convert it to the storage class closest to that affinity.Į.g. Tables may be created in the main database, the temp database, or in any attached database. The database in which the new table is created. To SQLite, it makes no difference whether you specify the column type as INT(1) or INTEGER(8), the resulting affinity will be INTEGER (however, SQLite remembers the actual string you used.). A CREATE TABLE command specifies the following attributes of the new table: The name of the new table. When you create a column, SQLite maps the type you specify to one of these storage classes. it doesn't matter whether an integer is stored as 8 bit or 64 bit if they are integers they add numerically.Ī column has an affinity, which is its preferred storage class. The storage class determines how the value behaves in expresisons etc. SQLite knows distinct data types (including integers of different sizes etc.) They are grouped into storage classes (INTEGER, REAL, TEXT, BLOB and NULL). Your app is responsible for enforcing these.It can be confusing and weird, though in my experience mostly harmless and sometimes helpful in practice. SQLite allows you to specify type facets like length, precision, and scale, but they are not enforced by the database engine. We recommend only using the four primitive SQLite type names: INTEGER, REAL, TEXT, and BLOB. One common gotcha is that using a column type of STRING will try to convert values to INTEGER or REAL, which can lead to unexpected results. The column type name does have an impact on the type affinity. won't apply any additional semantics to these names. You're free to use whatever column type name you want. SQLite uses a dynamic type system where the type of a value is associated with the value itself and not the column where it's stored. Using (var reader = command.ExecuteReader())Ĭonsole.WriteLine($"'.") command.CommandText name, julianday(finished) - julianday(started) AS length For more information, see Parameters.NETįor example, the following query reads a TimeSpan value from a REAL column in the result set. perhaps one of the most recurring issues people face is using DATETIME as a data type this actually results in an affinity of NUMERIC (the catchall for none of the other rules). Parameters can also be configured to use these alternative types. The plus point of how datatypes are handled is largely behind the scenes in that SQLite stores data efficiently. NET types can be read from alternative SQLite types. NET types are supported by, but values are ultimately coerced between these types and one of the four primitive types.NETĠ.0# format. APIs that return database values as an object will only ever return one of these four types. SQLite only has four primitive data types: INTEGER, REAL, TEXT, and BLOB.
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