format ( ix = index_name )) # Committing changes and closing the connection to the database fileĪfter we learned about how to create and modify SQLite databases, it’sĪbout time for some data retrieval. cursor () # Creating a new SQLite table with 1 columnĬ. New_field = 'my_1st_column' # name of the columnįield_type = 'INTEGER' # column data typeĬonn = sqlite3. Table_name2 = 'my_table_2' # name of the table to be created Table_name1 = 'my_table_1' # name of the table to be created The idea of the REPLACE statement is that when a UNIQUE or PRIMARY KEY constraint violation occurs, it does the following: First, delete the existing row that causes a constraint violation. Import sqlite3 sqlite_file = 'my_first_db.sqlite' # name of the sqlite database file A unique key is a constraint too, so if you declare a column as UNIQUE or PRIMARY KEY or such, you say 'This column can never contain duplicate values', so when you try to insert a row with the exact same value for that column than an existing row, a constraint failure happens, which is called a 'conflict' and which could be handled in several. Introduction to the SQLite REPLACE statement. Open a connection to an SQLite database file: In general, the only thing that needs to be done before we can performĪny operation on a SQLite database via Python’s sqlite3 module, is to Required, and no other obstacles we have to worry about. The Python Standard Library and is a nice and easy interface to SQLiteĭatabases: There are no server processes involved, no configurations The sqlite3 that we will be using throughout this tutorial is part of Referential integrity is enforced at the end of the statement by default. Strictly speaking, both inserts happen 'in parallel', but since this is a single statement, default FOREIGN KEY constraints will not complain. As discussed at Legacy Session Bulk INSERT Methods, the Session.bulkupdatemappings() method of Session is the legacy form of bulk update, which the ORM makes use of internally when interpreting a update() statement with primary key parameters given however, when using the legacy version, features such as support for session-synchronization. The complete Python code that I am using in this tutorial can be The final outer INSERT can now insert a fooid for every row: either the type pre-existed, or it was inserted in step 2.
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