If the database does not exist, Python will create a new database. The Python sqlite3 module will look for the database you specify. Finally, once we are done, we should close the connection using sqlite3.close() function. Then, we create the connection to the SQLite database file using nnect() function. To connect an SQLite database, first, we need to import the sqlite3 module. In this tutorial, we are going to learn how to connect to a sqlite3 database in python 3 programming. Sign up to +=1 for access to these, video downloads, and no ads.How to Connect to SQLite Database in Python 3 There exists 9 quiz/question(s) for this tutorial. Sign up to +=1 for access to these, video downloads, and no ads. There exists 5 challenge(s) for this tutorial. In the next tutorial, we're going to show an example of how you might graph this data from the database. Since you can be explicit about the order of columns, coding this in should not be a challenge.Ĭ.execute('SELECT * FROM stuffToPlot WHERE value = 3')Ĭ.execute('SELECT * FROM stuffToPlot WHERE unix > 1452554972')Ĭ.execute('SELECT value, datestamp FROM stuffToPlot WHERE unix > 1452554972') You use indexing like this to reference specific elements. Also note that this time we're printing out row. Here, we're selecting value and datestamp, in that order. In the database, datestamp comes first, value second, and there are of course other columns. This time, we're selecting the value and datestamp columns. Not only can you specify which rows you want, you can also specify which columns, and even in what order: c.execute('SELECT value, datestamp FROM stuffToPlot WHERE unix > 1452554972') In this case, we're selecting all of the rows that have the value in the unix column greater than 1452554972 (you will want to consider changing that value depending on when you are doing the tutorial). What about comparison operators? No problem: c.execute('SELECT * FROM stuffToPlot WHERE unix > 1452554972') This time, we only referenced the data in the table where the value for the "value" column was 3. Let's try to add in some logic next: c.execute('SELECT * FROM stuffToPlot WHERE value = 3') In the above case, we're just outputting the entire table. Also, note that we are not needing to do a mit(). Finally, we can either just print the data, or iterate through it, like pasting the information. The select is like you highlighted, then you do c.fetchall(), so this is like you are copying your highlighted information. Think of this again, much like the computer cursor. Then, to access the data from the cursor, we use c.fetchall(). Notice that when we execute the query, we're executing it with the cursor as usual. Next, let's create another function, calling it read_from_db: def read_from_db(): Let's see what I mean:Ĭ.execute("CREATE TABLE IF NOT EXISTS stuffToPlot(unix REAL, datestamp TEXT, keyword TEXT, value REAL)")Ĭ.execute("INSERT INTO stuffToPlot VALUES(1452549219,' 13:53:39','Python',6)")ĭate = str((unix).strftime('%Y-%m-%d %H:%M:%S'))Ĭ.execute("INSERT INTO stuffToPlot (unix, datestamp, keyword, value) VALUES (?, ?, ?, ?)", While we can query the entire table, we can instead just query a single column, or even based on specific row values. Reading from a database is where the power of using something like SQLite over a flat file starts to make sense. In the previous tutorials, we've covered creating a database and populating one, now we need to learn how to read from the database.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |