diff --git a/MainProject.Tests/Controllers/UserController_Tests.cs b/MainProject.Tests/Controllers/UserController_Tests.cs
index 7ece72f..76a1b29 100644
--- a/MainProject.Tests/Controllers/UserController_Tests.cs
+++ b/MainProject.Tests/Controllers/UserController_Tests.cs
@@ -29,7 +29,7 @@ namespace BasicDotnetTemplate.MainProject.Tests;
 [TestClass]
 public class UserControllerTests
 {
-    private IMapper _mapper;
+    private IMapper? _mapper;
 
     [TestInitialize]
     public void Setup()
diff --git a/MainProject.Tests/Core/AutoMapperConfiguration_Tests.cs b/MainProject.Tests/Core/AutoMapperConfiguration_Tests.cs
index 77b4e48..d52a962 100644
--- a/MainProject.Tests/Core/AutoMapperConfiguration_Tests.cs
+++ b/MainProject.Tests/Core/AutoMapperConfiguration_Tests.cs
@@ -19,7 +19,7 @@ namespace BasicDotnetTemplate.MainProject.Tests;
 [TestClass]
 public class AutoMapperConfiguration_Tests
 {
-    private IMapper _mapper;
+    private IMapper? _mapper;
 
     [TestInitialize]
     public void Setup()
@@ -53,13 +53,13 @@ public class AutoMapperConfiguration_Tests
                 },
                 IsTestUser = true
             };
-            UserDto data = _mapper.Map<UserDto>(user);
+            UserDto? data = _mapper?.Map<UserDto>(user);
 
-            Assert.IsTrue(data.Guid == user.Guid);
-            Assert.IsTrue(data.Username == user.Username);
-            Assert.IsTrue(data.FirstName == user.FirstName);
-            Assert.IsTrue(data.LastName == user.LastName);
-            Assert.IsTrue(data.Email == user.Email);
+            Assert.IsTrue(data?.Guid == user.Guid);
+            Assert.IsTrue(data?.Username == user.Username);
+            Assert.IsTrue(data?.FirstName == user.FirstName);
+            Assert.IsTrue(data?.LastName == user.LastName);
+            Assert.IsTrue(data?.Email == user.Email);
         }
         catch (Exception ex)
         {
diff --git a/MainProject.Tests/Models/Api/Response/User/GetUserResponse_Tests.cs b/MainProject.Tests/Models/Api/Response/User/GetUserResponse_Tests.cs
index 1ab43ce..c1cb1c1 100644
--- a/MainProject.Tests/Models/Api/Response/User/GetUserResponse_Tests.cs
+++ b/MainProject.Tests/Models/Api/Response/User/GetUserResponse_Tests.cs
@@ -19,7 +19,7 @@ namespace BasicDotnetTemplate.MainProject.Tests;
 [TestClass]
 public class GetUserResponse_Tests
 {
-    private IMapper _mapper;
+    private IMapper? _mapper;
 
     [TestInitialize]
     public void Setup()
@@ -97,7 +97,7 @@ public class GetUserResponse_Tests
                 },
                 IsTestUser = true
             };
-            UserDto data = _mapper.Map<UserDto>(user);
+            UserDto? data = _mapper?.Map<UserDto>(user);
             var getUserResponse = new GetUserResponse(200, "This is a test message", data);
             Assert.IsTrue(getUserResponse.Status == 200 && getUserResponse.Message == "This is a test message" && getUserResponse.Data == data);
         }
diff --git a/MainProject/Core/Database/SqlServerContext.cs b/MainProject/Core/Database/SqlServerContext.cs
index e9b15ab..1a7cb22 100644
--- a/MainProject/Core/Database/SqlServerContext.cs
+++ b/MainProject/Core/Database/SqlServerContext.cs
@@ -13,6 +13,20 @@ namespace BasicDotnetTemplate.MainProject.Core.Database
         }
 
         public DbSet<User> Users { get; set; }
+
+
+        protected override void OnModelCreating(ModelBuilder modelBuilder)
+        {
+            modelBuilder.Entity<User>()
+                .HasIndex(x => x.Email, "IX_Email");
+
+            modelBuilder.Entity<User>()
+                .HasIndex(x => x.Username, "IX_Username");
+
+            modelBuilder.Entity<User>()
+                .HasIndex(x => new { x.IsDeleted, x.Guid }, "IX_IsDeleted_Guid")
+                .HasFilter("[IsDeleted] = 0");
+        }
     }
 }
 
diff --git a/MainProject/Migrations/20250312234517_AlterTableUserMaxLengthIndexes.Designer.cs b/MainProject/Migrations/20250312234517_AlterTableUserMaxLengthIndexes.Designer.cs
new file mode 100644
index 0000000..b22b8a0
--- /dev/null
+++ b/MainProject/Migrations/20250312234517_AlterTableUserMaxLengthIndexes.Designer.cs
@@ -0,0 +1,170 @@
+// <auto-generated />
+using System;
+using BasicDotnetTemplate.MainProject.Core.Database;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace MainProject.Migrations
+{
+    [DbContext(typeof(SqlServerContext))]
+    [Migration("20250312234517_AlterTableUserMaxLengthIndexes")]
+    partial class AlterTableUserMaxLengthIndexes
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "9.0.2")
+                .HasAnnotation("Relational:MaxIdentifierLength", 128);
+
+            SqlServerModelBuilderExtensions.UseIdentityColumns(modelBuilder);
+
+            modelBuilder.Entity("BasicDotnetTemplate.MainProject.Models.Database.SqlServer.Role", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("int");
+
+                    SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<int>("Id"));
+
+                    b.Property<DateTime>("CreationTime")
+                        .HasColumnType("datetime2");
+
+                    b.Property<int>("CreationUserId")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("DeletionTime")
+                        .HasColumnType("datetime2");
+
+                    b.Property<int>("DeletionUserId")
+                        .HasColumnType("int");
+
+                    b.Property<string>("Guid")
+                        .IsRequired()
+                        .HasMaxLength(45)
+                        .HasColumnType("nvarchar(45)");
+
+                    b.Property<bool>("IsDeleted")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<DateTime>("UpdateTime")
+                        .HasColumnType("datetime2");
+
+                    b.Property<int>("UpdateUserId")
+                        .HasColumnType("int");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("Role");
+                });
+
+            modelBuilder.Entity("BasicDotnetTemplate.MainProject.Models.Database.SqlServer.User", b =>
+                {
+                    b.Property<int>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("int");
+
+                    SqlServerPropertyBuilderExtensions.UseIdentityColumn(b.Property<int>("Id"));
+
+                    b.Property<DateTime>("CreationTime")
+                        .HasColumnType("datetime2");
+
+                    b.Property<int>("CreationUserId")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("DeletionTime")
+                        .HasColumnType("datetime2");
+
+                    b.Property<int>("DeletionUserId")
+                        .HasColumnType("int");
+
+                    b.Property<string>("Email")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
+
+                    b.Property<string>("FirstName")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
+
+                    b.Property<string>("Guid")
+                        .IsRequired()
+                        .HasMaxLength(45)
+                        .HasColumnType("nvarchar(45)");
+
+                    b.Property<bool>("IsDeleted")
+                        .HasColumnType("bit");
+
+                    b.Property<bool>("IsTestUser")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("LastName")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
+
+                    b.Property<string>("Password")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("PasswordHash")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("PasswordSalt")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<int>("RoleId")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("UpdateTime")
+                        .HasColumnType("datetime2");
+
+                    b.Property<int>("UpdateUserId")
+                        .HasColumnType("int");
+
+                    b.Property<string>("Username")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("RoleId");
+
+                    b.HasIndex(new[] { "Email" }, "IX_Email");
+
+                    b.HasIndex(new[] { "IsDeleted", "Guid" }, "IX_IsDeleted_Guid")
+                        .HasFilter("[IsDeleted] = 0");
+
+                    b.HasIndex(new[] { "Username" }, "IX_Username");
+
+                    b.ToTable("Users");
+                });
+
+            modelBuilder.Entity("BasicDotnetTemplate.MainProject.Models.Database.SqlServer.User", b =>
+                {
+                    b.HasOne("BasicDotnetTemplate.MainProject.Models.Database.SqlServer.Role", "Role")
+                        .WithMany()
+                        .HasForeignKey("RoleId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Role");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}
diff --git a/MainProject/Migrations/20250312234517_AlterTableUserMaxLengthIndexes.cs b/MainProject/Migrations/20250312234517_AlterTableUserMaxLengthIndexes.cs
new file mode 100644
index 0000000..862a803
--- /dev/null
+++ b/MainProject/Migrations/20250312234517_AlterTableUserMaxLengthIndexes.cs
@@ -0,0 +1,165 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace MainProject.Migrations
+{
+    /// <inheritdoc />
+    public partial class AlterTableUserMaxLengthIndexes : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AlterColumn<string>(
+                name: "Username",
+                table: "Users",
+                type: "nvarchar(200)",
+                maxLength: 200,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "LastName",
+                table: "Users",
+                type: "nvarchar(200)",
+                maxLength: 200,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Guid",
+                table: "Users",
+                type: "nvarchar(45)",
+                maxLength: 45,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "FirstName",
+                table: "Users",
+                type: "nvarchar(200)",
+                maxLength: 200,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Email",
+                table: "Users",
+                type: "nvarchar(200)",
+                maxLength: 200,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.AddColumn<bool>(
+                name: "IsTestUser",
+                table: "Users",
+                type: "bit",
+                nullable: false,
+                defaultValue: false);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Guid",
+                table: "Role",
+                type: "nvarchar(45)",
+                maxLength: 45,
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(max)");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Email",
+                table: "Users",
+                column: "Email");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_IsDeleted_Guid",
+                table: "Users",
+                columns: new[] { "IsDeleted", "Guid" },
+                filter: "[IsDeleted] = 0");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Username",
+                table: "Users",
+                column: "Username");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Email",
+                table: "Users");
+
+            migrationBuilder.DropIndex(
+                name: "IX_IsDeleted_Guid",
+                table: "Users");
+
+            migrationBuilder.DropIndex(
+                name: "IX_Username",
+                table: "Users");
+
+            migrationBuilder.DropColumn(
+                name: "IsTestUser",
+                table: "Users");
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Username",
+                table: "Users",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(200)",
+                oldMaxLength: 200);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "LastName",
+                table: "Users",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(200)",
+                oldMaxLength: 200);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Guid",
+                table: "Users",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(45)",
+                oldMaxLength: 45);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "FirstName",
+                table: "Users",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(200)",
+                oldMaxLength: 200);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Email",
+                table: "Users",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(200)",
+                oldMaxLength: 200);
+
+            migrationBuilder.AlterColumn<string>(
+                name: "Guid",
+                table: "Role",
+                type: "nvarchar(max)",
+                nullable: false,
+                oldClrType: typeof(string),
+                oldType: "nvarchar(45)",
+                oldMaxLength: 45);
+        }
+    }
+}
diff --git a/MainProject/Migrations/SqlServerContextModelSnapshot.cs b/MainProject/Migrations/SqlServerContextModelSnapshot.cs
index 8368bbd..e0eb021 100644
--- a/MainProject/Migrations/SqlServerContextModelSnapshot.cs
+++ b/MainProject/Migrations/SqlServerContextModelSnapshot.cs
@@ -44,7 +44,8 @@ namespace MainProject.Migrations
 
                     b.Property<string>("Guid")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(45)
+                        .HasColumnType("nvarchar(45)");
 
                     b.Property<bool>("IsDeleted")
                         .HasColumnType("bit");
@@ -86,22 +87,29 @@ namespace MainProject.Migrations
 
                     b.Property<string>("Email")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
 
                     b.Property<string>("FirstName")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
 
                     b.Property<string>("Guid")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(45)
+                        .HasColumnType("nvarchar(45)");
 
                     b.Property<bool>("IsDeleted")
                         .HasColumnType("bit");
 
+                    b.Property<bool>("IsTestUser")
+                        .HasColumnType("bit");
+
                     b.Property<string>("LastName")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
 
                     b.Property<string>("Password")
                         .IsRequired()
@@ -126,12 +134,20 @@ namespace MainProject.Migrations
 
                     b.Property<string>("Username")
                         .IsRequired()
-                        .HasColumnType("nvarchar(max)");
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
 
                     b.HasKey("Id");
 
                     b.HasIndex("RoleId");
 
+                    b.HasIndex(new[] { "Email" }, "IX_Email");
+
+                    b.HasIndex(new[] { "IsDeleted", "Guid" }, "IX_IsDeleted_Guid")
+                        .HasFilter("[IsDeleted] = 0");
+
+                    b.HasIndex(new[] { "Username" }, "IX_Username");
+
                     b.ToTable("Users");
                 });
 
diff --git a/MainProject/Models/Database/SqlServer/Base.cs b/MainProject/Models/Database/SqlServer/Base.cs
index 6c89599..d90ad6a 100644
--- a/MainProject/Models/Database/SqlServer/Base.cs
+++ b/MainProject/Models/Database/SqlServer/Base.cs
@@ -1,18 +1,22 @@
-namespace BasicDotnetTemplate.MainProject.Models.Database.SqlServer
+using System.ComponentModel.DataAnnotations;
+using Microsoft.EntityFrameworkCore;
+
+namespace BasicDotnetTemplate.MainProject.Models.Database.SqlServer;
+
+public class Base
 {
-    public class Base
-    {
-        public int Id { get; set; }
-        public string Guid { get; set; }
-        public bool IsDeleted { get; set; }
-        public DateTime CreationTime { get; set; }
-        public int CreationUserId { get; set; }
-        public DateTime UpdateTime { get; set; }
-        public int UpdateUserId { get; set; }
-        public DateTime DeletionTime { get; set; }
-        public int DeletionUserId { get; set; }
-    }
+    public int Id { get; set; }
+    [MaxLength(45)]
+    public string Guid { get; set; }
+    public bool IsDeleted { get; set; }
+    public DateTime CreationTime { get; set; }
+    public int CreationUserId { get; set; }
+    public DateTime UpdateTime { get; set; }
+    public int UpdateUserId { get; set; }
+    public DateTime DeletionTime { get; set; }
+    public int DeletionUserId { get; set; }
 }
 
 
 
+
diff --git a/MainProject/Models/Database/SqlServer/User.cs b/MainProject/Models/Database/SqlServer/User.cs
index 7e5f149..4e0f0e8 100644
--- a/MainProject/Models/Database/SqlServer/User.cs
+++ b/MainProject/Models/Database/SqlServer/User.cs
@@ -1,12 +1,18 @@
+using System.ComponentModel.DataAnnotations;
 using System.Text.Json.Serialization;
+using Microsoft.EntityFrameworkCore;
 
 namespace BasicDotnetTemplate.MainProject.Models.Database.SqlServer;
 
 public class User : Base
 {
+    [MaxLength(200)]
     public required string Username { get; set; }
+    [MaxLength(200)]
     public required string FirstName { get; set; }
+    [MaxLength(200)]
     public required string LastName { get; set; }
+    [MaxLength(200)]
     public required string Email { get; set; }
     public required string PasswordSalt { get; set; }
     public required string PasswordHash { get; set; }
diff --git a/MainProject/Utils/JwtTokenUtils.cs b/MainProject/Utils/JwtTokenUtils.cs
index 7c427a0..3786ec2 100644
--- a/MainProject/Utils/JwtTokenUtils.cs
+++ b/MainProject/Utils/JwtTokenUtils.cs
@@ -54,8 +54,8 @@ public class JwtTokenUtils
         string? guid = null;
 
         if (
-            String.IsNullOrEmpty(_jwtKey) || 
-            String.IsNullOrEmpty(_jwtIssuer) || 
+            String.IsNullOrEmpty(_jwtKey) ||
+            String.IsNullOrEmpty(_jwtIssuer) ||
             String.IsNullOrEmpty(_jwtAudience)
         )
         {
@@ -68,7 +68,7 @@ public class JwtTokenUtils
             token = authorizations[1];
         }
 
-        if(!String.IsNullOrEmpty(token))
+        if (!String.IsNullOrEmpty(token))
         {
             try
             {
@@ -97,9 +97,9 @@ public class JwtTokenUtils
                     }
                 }
             }
-            catch(Exception exception)
+            catch (Exception exception)
             {
-                Logger.Error($"[JwtTokenUtils][ValidateToken] | {exception}");
+                Logger.Error(exception, $"[JwtTokenUtils][ValidateToken]");
                 return guid;
             }
         }