[英]How do I check in SQLite whether a database exists C#
I'm currently programming an app in C# and using sqlite as an embedded database. 我目前正在使用C#编写应用程序并使用sqlite作为嵌入式数据库。 I have got my app to create a new database on start-up, but how do I get it to check if the database exists?
我有我的应用程序在启动时创建一个新的数据库,但我如何让它检查数据库是否存在? If it does exist how do I get it to use it, and if not how to create a new database?
如果确实存在,我如何使用它,如果不存在如何创建新数据库?
This is what i have so far: 这是我到目前为止:
private void MainWindow_Loaded(object sender, EventArgs e)
{
SQLiteConnection sqlite_conn;
SQLiteCommand sqlite_cmd;
bool newdb = false;
if (newdb == true)
{
sqlite_conn = new SQLiteConnection("DataSource=database.db;Version=3;");
sqlite_conn.Open();
MessageBox.Show("31");
}
else
{
sqlite_conn = new SQLiteConnection("Data Source=database.db;Version=3;New=True;Compress=True;");
sqlite_conn.Open();
sqlite_cmd = sqlite_conn.CreateCommand();
sqlite_cmd.CommandText = "CREATE TABLE Client (id integer primary key, Title varchar(100),Name varchar(100),Surname varchar(100),Dateofbirth DateTime , Propertyname varchar(100),Moveindate DateTime,Relationship varchar(100),Spouse varchar(100),Gender varchar(100), spTitle varchar(100),SpouseName varchar(100),SpouseSurname varchar(100),spDateofbirth DateTime ,spRelationship varchar(100),spSpouse varchar(100),spGender varchar(100));";
sqlite_cmd.ExecuteNonQuery();
}
sqlite_conn.Close();
MessageBox.Show("dasdas");
}
How about: 怎么样:
if(File.Exists("database.db"))
Edit: Changed path to match source in original code. 编辑:更改了原始代码中匹配源的路径。
public async Task<bool> IsDbExists(string fileName)
{
try
{
var item = await ApplicationData.Current.LocalFolder.GetFileAsync(fileName);
var db = new SQLiteConnection(DbHelper.DBPATH);
var tb1 = db.GetTableInfo("Domain");
var tb2 = db.GetTableInfo("Account");
var tb3 = db.GetTableInfo("Product");
var tb4 = db.GetTableInfo("Review");
if (item == null || tb1.Count == 0 || tb2.Count == 0 || tb3.Count == 0 || tb4.Count == 0)
{
return false;
}
else
{
return true;
}
}
catch
{
return false;
}
}
This is one of the solution
privat string _dataSource = @"H:\Ik.db";
private SQLiteConnection _connection;
private SQLiteCommand _command;
private void connectToSQLite()
{
using (SQLiteConnection _connection = new SQLiteConnection())
{
if (File.Exists(@"H:\Ik.db"))
{
_connection.ConnectionString = $"Data Source={_dataSource};Version=3";
_connection.Open();
using (SQLiteCommand _command = new SQLiteCommand())
{
_command.Connection = _connection;
_command.CommandText = "CREATE TABLE IF NOT EXISTS Kunden ( id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, Lastname VARCHAR(100) NOT NULL, " +
"name VARCHAR(100) NOT NULL, Code VARCHAR(100) NOT NULL, City VARCHAR(100) NOT NULL);";
try
{
_command.ExecuteNonQuery();
MessageBox.Show($"You Connected to local Data Base under {_dataSource} Sucssefuly");
}
catch (Exception)
{
throw;
}
}
}
else
{
SQLiteConnection.CreateFile(@"H:\Ik.db");
}
}
}
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