WIP db provider support for Mysql and Postgres

src/NadekoBot/Db/SqliteContext.cs

@@ -0,0 +1,30 @@
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+
+namespace NadekoBot.Services.Database;
+
+public sealed class SqliteContext : NadekoContext
+{
+    private readonly string _connectionString;
+
+    protected override string CurrencyTransactionOtherIdDefaultValue
+        => "NULL";
+    protected override string DiscordUserLastXpGainDefaultValue
+        => "datetime('now', '-1 years')";
+    protected override string LastLevelUpDefaultValue
+        => "datetime('now')";
+
+    public SqliteContext(string connectionString = "Data Source=data/NadekoBot.db", int commandTimeout = 60)
+    {
+        _connectionString = connectionString;
+        Database.SetCommandTimeout(commandTimeout);
+    }
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+        base.OnConfiguring(optionsBuilder);
+        var builder = new SqliteConnectionStringBuilder(_connectionString);
+        builder.DataSource = Path.Combine(AppContext.BaseDirectory, builder.DataSource);
+        optionsBuilder.UseSqlite(builder.ToString());
+    }
+}