![]() ![]() This example will rename our existing employees table to _employees_old. SELECT employee_id, last_name, first_name, hire_date INSERT INTO employees (employee_id, last_name, first_name, hire_date) ( employee_id INTEGER PRIMARY KEY AUTOINCREMENT,Īnd we wanted to change the datatype of the last_name field to VARCHAR, we could do the following: PRAGMA foreign_keys=off ĪLTER TABLE employees RENAME TO _employees_old Let's look at an example that shows how to modify a column in a SQLite table.įor example, if we had an employees table that had a column called last_name that was defined as a CHAR datatype: CREATE TABLE employees The syntax to MODIFY A COLUMN in a table in SQLite is: PRAGMA foreign_keys=off ĪLTER TABLE table1 RENAME TO _table1_old Instead you will need to rename the table, create a new table, and copy the data into the new table. Private void clickFoodDialogList(object sender, DialogClickEventArgs args)Ĭonsole.WriteLine ("Selected: 条", oldDataCount)).You can not use the ALTER TABLE statement to modify a column in SQLite. Var NxtAct = new Intent(this, typeof(RegisterActivity)) Var NxtAct = new Intent(this, typeof(LoginActivity)) īutton button1 = FindViewById (Resource.Id.Register) Var NxtAct = new Intent(this, typeof(StartActivity)) īutton button = FindViewById (Resource.Id.Login) If (conn.ExecuteScalar ("Select Count(*) From Login") != 0) If (conn.ExecuteScalar ("SELECT count(*) FROM sqlite_master WHERE type = 'table' AND name = 'Login'") = 0) Using (var conn = new SQLite.SQLiteConnection(Path.Combine(().ToString(), "database.sqlite"))) Get our button from the layout resource, Set our view from the "main" layout resource Protected override void OnCreate(Bundle bundle) You can rate examples to help us improve the quality of examples. These are the top rated real world C# (CSharp) examples of extracted from open source projects. C# (CSharp) SQLite SQLiteConnection.ExecuteScalar - 24 examples found. The SQLite library for C# can be installed via NuGet package manager. The result is returned as a `string` and stored in the `name` variable. It executes a query that selects the name from a row in `mytable` with `id` equal to 1. This code opens a connection to the same SQLite database as the previous example. String name = (string)connection.ExecuteScalar(query) String query = "SELECT name FROM mytable WHERE id=1" The result is returned as an `int` and stored in the `count` variable. It then executes a query that counts the number of rows in a table named `mytable`. This code opens a connection to an SQLite database stored in a file named `mydatabase.sqlite`. Int count = (int)connection.ExecuteScalar(query) String query = "SELECT COUNT(*) FROM mytable" SQLiteConnection connection = new SQLiteConnection("Data Source=mydatabase.sqlite") The `ExecuteScalar` method of this class can be used to execute an SQL query that returns a single result. One of the key features of the SQLite library for C# is the `SQLiteConnection` class, which represents a connection to an SQLite database. C# has an SQLite library that provides a simple API to interact with SQLite databases. ![]() ![]() It can be used with many programming languages, including C#. SQLite is a popular embedded SQL database engine.
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