VALUES( 1),( 2),( 3),( null),( 3) Code language: SQL (Structured Query Language) ( sql ) Second, insert five rows into the t1 table: INSERT INTO t1(c) SQLite COUNT() function illustrationįirst, create a table called t1 that has one column: CREATE TABLE t1(c INTEGER) Code language: SQL (Structured Query Language) ( sql ) The COUNT(*) function returns the number of rows in a table, including the rows including NULL and duplicates. SQLite provides another syntax of the COUNT() function: COUNT(*) Code language: SQL (Structured Query Language) ( sql ) The expression can be a column or an expression that involves columns to which the function COUNT() is applied. DISTINCT: if you explicitly use the DISTINCT option, the COUNT function counts only unique and non-null values.The COUNT() function uses the ALL option by default if you skip it. ALL: when you specify all, the COUNT() function counts all non-null values include duplicates.The following describes the meanings of ALL and DISTINCT options: ![]() ![]() The COUNT function behaves according to the arguments that you pass into it and the option ALL or DISTINCT that you specify. The following illustrates the basic syntax of the COUNT function: COUNT( expression) Code language: SQL (Structured Query Language) ( sql ) Arguments The function COUNT() is an aggregate function that returns the number of items in a group.įor example, you can use the COUNT() function to get the number of tracks from the tracks table, the number of artists from the artists table, and so on. In this tutorial, you have learned how to develop a Python program to query data from tables in an SQLite database.Summary: in this tutorial, you will learn how to use SQLite COUNT function to get the number of items in a group. Select_all_tasks(conn) Code language: Python ( python )ĭef create_connection (db_file): """ create a database connection to the SQLite databaseĭef select_task_by_priority (conn, priority): """ This main() function creates a connection to the database C:\sqlite\db\pythonsqlite.db and calls the functions to query all rows from the tasks table and select tasks with priority 1: def main ():ĭatabase = r"C:\sqlite\db\pythonsqlite.db" # create a database connection The fetchall() method fetched all matching tasks by the priority. When the cursor executed the SELECT statement, it substituted the question mark ( ?) by the priority argument. The question mark ( ?) in the query is the placeholder. In the select_task_by_priority() function, we selected the tasks based on a particular priority. This function query tasks by priority: def select_task_by_priority (conn, priority): """Ĭur.execute( "SELECT * FROM tasks WHERE priority=?", (priority,)) In the select_all_tasks() function, we created a cursor, executed the SELECT statement, and called the fetchall() to fetch all tasks from the tasks table. Print(row) Code language: Python ( python ) This function selects all rows from the tasks table and displays the data: def select_all_tasks (conn): """ Return conn Code language: Python ( python ) ![]() In the following example, we will use the tasks table created in the creating tables tutorial.įirst, create a connection to an SQLite database specified by a file: def create_connection (db_file): """ create a database connection to the SQLite database Finally, loop the cursor and process each row individually.After that, call the fetchall() method of the cursor object to fetch the data. ![]() Next, create a Cursor object using the cursor method of the Connection object.First, establish a connection to the SQLite database by creating a Connection object.To query data in an SQLite database from Python, you use these steps: Summary: in this tutorial, we will show you step by step how to query data in SQLite from Python.
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