![]() If the name entered already exists in the writers table then the database record. The contents of the ‘person’ table now looks as follows. The main method asks the user if they want to update or add new writer entries. Confirm error updating person information and exit.Ĭonsole.WriteLine("Error updating person information.") Confirm successful updating of person information.Ĭonsole.WriteLine("Person information updated successfully.") Query text incorporated into SQL command. Message confirming unsuccessful database connection.Ĭonsole.WriteLine("Database connection unsuccessful.") Message confirming incorrect database location.Ĭonsole.WriteLine("Error locating database.") Ĭonnect = new SqliteConnection("Data Source=" + database + " " + The declaration and execution of the SQL statement is wrapped in a ‘try-catch-finally’ block to catch any errors that may arise and close the database connection at the end. The SQL statement is then executed and a confirmation message is displayed. The other parameters are for updating the ‘lastname’ and ‘title’ fields against the record. One of the parameters is for an ‘id’, so that only the specified record is updated, in this case, the record with an ‘id’ of five. If successfully found, a connection to the database is established, then the query parameters are defined as variables, which are bound in to the SQL statement. ![]() If it doesn’t, a message is displayed and execution of the program is halted. Firstly, a check is made to see if the database file actually exists. Updating data follows the same pattern as inserting data. The following example updates the record in the ‘person’ table that was added in the example for inserting data. Please show your love and support by sharing this post.In order to update data in an SQLite database, the SQL ‘Update’ statement needs to be used. It was published 25 Mar, 2023 (and was last revised 02 Apr, 2023). When this query is executed, it will result in " hits" column being incremented by 1 since the slug " lorem-ipsum" already exists: ('Lorem Ipsum', 'lorem-ipsum', COALESCE(( INSERT OR REPLACE INTO `blog_post` (`title`, `slug`, `hits`) VALUES Otherwise, it will increment the " hits" column: The following UPSERT query will return " 1" for the " hits" column when the inner query does not return a match. This allows you to have the ability to set a default value in the event that the inner query does not return a match. In this syntax, using the COALESCE function allows you to specify two or more arguments, where the function returns the first non-null argument. INSERT OR REPLACE INTO `table` (`unique_col`, `some_col`) An example that creates a table test, inserts a couple of rows and proceeds to showcase how to update or delete rows. You can use the following INSERT OR REPLACE syntax to perform an UPSERT: For example, the following query will result in a new record being added to the table:Īfter this query is executed, the table will look like the following: When the uniqueness constraint does not fail, a new record is created. This would result in " hits" column being incremented by 1 as the slug " lorem-ipsum" already exists: ON CONFLICT (`slug`) DO UPDATE SET hits = hits + 1 INSERT INTO `blog_post` (`title`, `slug`) When you use an UPSERT query like the following, it would perform an UPDATE when the INSERT violates the uniqueness constraint: This would result in the following SQLite table: INSERT INTO `blog_post` (`title`, `slug`) VALUES In this UPSERT operation, the " ON CONFLICT" clause specifies the conflict target, which is the column (or columns) that must have a unique constraint or unique index defined for the UPSERT operation to work correctly.įor example, let's suppose you have the following " blog_post" table, with the " slug" column having the UNIQUE constraint: ON CONFLICT (`unique_col`) DO UPDATE SET `some_col` = 'some_col_new_val' INSERT INTO table (`unique_col`) VALUES ('unique_val') Starting with SQLite v3.24.0, you can use the ON CONFLICT clause to perform an UPSERT, using the following syntax: Using either of these will allow you to perform an INSERT or UPDATE in a single query, based on whether a uniqueness constraint is violated or not. In SQLite, you can do an UPSERT operation in the following ways:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |