mode line) has got nothing to do with creating a foreign key. Note that the first line of my command (. This time we can see the details of the foreign key constraint. Now let’s check the table for foreign key constraints again.mode line If you need to reconstruct any indexes, triggers, or views, do that after the ALTER TABLE statement that renames the table (just prior to COMMIT). PRAGMA foreign_keys = OFF įOREIGN KEY(TypeId) REFERENCES Types(TypeId) The following code adds a foreign key to our table by creating a new table with a foreign key constraint, transferring the data to that table, dropping the original table, then renaming the new table to the name of the original table. (That’s blank because there are no foreign key constraints on this table.) We can verify that there are no foreign keys by running the following command: PRAGMA foreign_key_list(Pets) Notice that I didn’t create a foreign key. Two tables, because one ( Types) will have the primary key and the other ( Pets) will have the foreign key. CREATE TABLE Types(Īctually, here I created two tables and populated them with data. Original Table Without Foreign Keyįirst, let’s create a table without a foreign key and populate it with data. To make it somewhat realistic, we’ll make sure the table already contains data. The SQLite documentation recommends a 12 step process for making schema changes to a table.įor the purposes of this article, we’ll just deal with adding a foreign key. There’s more than one way to do this, but there is a recommended way. Therefore, the only way you can “add” a foreign key to an existing table in SQLite is to create a new table with a foreign key, then transfer the data to the new table. In other words, you can’t use ALTER TABLE to add a foreign key to an existing table like you can in other database management systems. The only things you can do with ALTER TABLE in SQLite is rename a table, rename a column within a table, or add a new column to an existing table. In this tutorial, you have learned how to dump data into a text file using the SQLite dump command and other commands.SQLite supports a very limited subset of the ALTER TABLE statement. To dump data from other tables, you need to issue the SELECT statements to query data from those tables. sqlite> select * from artists Code language: SQL (Structured Query Language) ( sql )Ĭheck the content of the data.sql file, if everything is fine, you will see the following output: The following command returns data from the artists table. Third, issue the SELECT statements to query data from a table that you want to dump. The following command sets the output file to the data.sql file. Second, set the output to a text file instead of the default standard output. mode insert Code language: CSS ( css )įrom now on, every SELECT statement will issue the result as the INSERT statements instead of pure text data. To dump the data of a table into a text file, you use these steps:įirst, set the mode to insert using the. Dump data of one or more tables into a file The following picture shows the content of the chinook_structure.sql file. The following commands set the output file to chinook_structure.sql file and save the table structures into the chinook_structure.sql file: sqlite>. To dump the table structures in a database, you use the. Dump tables structure only using schema command The following picture shows the contents of the albums.sql file. quit Code language: JavaScript ( javascript ) For example, the following command saves the albums table to the albums.sql file. To dump a specific table, you specify the table name after the. exit Code language: JavaScript ( javascript ) Dump a specific table using the SQLite dump command The following commands specify the output of the dump file to chinook.sql and dump the chinook database into the chinook.sql file. To issue the output to a file, you use the. dump command outputs the SQL statements on screen. dump command converts the entire structure and data of an SQLite database into a single text file.īy default, the. To dump a database into a file, you use the. Sqlite> Code language: JavaScript ( javascript ) The following command opens a new SQLite database connection to the chinook.db file. Dump the entire database into a file using the SQLite dump command dump command that gives you the ability to dump the entire database or tables into a text file. Also, you can use special commands, which are known as dot commands to perform various useful database operations. SQLite project delivers the sqlite3 tool that allows you to interact with the SQLite database using a command-line program.īy using the sqlite3 tool, you can use the SQL statements to query or update data in the database. Summary: in this tutorial, you will learn how to use the SQLite dump command to back up and restore a database.
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