WIP db provider support for Mysql and Postgres

src/NadekoBot/Db/MysqlContext.cs

@@ -0,0 +1,42 @@
+using Microsoft.EntityFrameworkCore;
+using NadekoBot.Db.Models;
+
+namespace NadekoBot.Services.Database;
+
+public sealed class MysqlContext : NadekoContext
+{
+    private readonly string _connStr;
+    private readonly string _version;
+
+    protected override string CurrencyTransactionOtherIdDefaultValue
+        => "NULL";
+    protected override string DiscordUserLastXpGainDefaultValue
+        => "(UTC_TIMESTAMP - INTERVAL 1 year)";
+    protected override string LastLevelUpDefaultValue
+        => "(UTC_TIMESTAMP)";
+
+    public MysqlContext(string connStr = "Server=localhost", string version = "8.0")
+    {
+        _connStr = connStr;
+        _version = version;
+    }
+
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+    {
+        base.OnConfiguring(optionsBuilder);
+        optionsBuilder
+            .UseLowerCaseNamingConvention()
+            .UseMySql(_connStr, ServerVersion.Parse(_version));
+    }
+
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        base.OnModelCreating(modelBuilder);
+        
+        // mysql is case insensitive by default
+        // we can set binary collation to change that
+        modelBuilder.Entity<ClubInfo>()
+                    .Property(x => x.Name)
+                    .UseCollation("utf8mb4_bin");
+    }
+}