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in 매개 변수
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// 여기서의 in은 ref readonly처럼 작동함 함수 call시에는 in을 쓰거나 말거나 동일 void PrintDate(in DateTime date) { Console.WriteLine(date); } |
null 관련 연산자
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// 오래전 instance = instance == null ? value : instance; // 기존 instance = instance ?? value; // 현재 instance ??= value; |
Auto Property
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// C# 6.0 Auto property public string Name { get; set; } = "Karu"; |
Index 연산
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// C# 8.0 인덱스 연산 string str = "Rolling Ress"; var last = str[^1]; // 's' var sub = str[0..4]; // "Roll", 구간은 [0, 4) |
ICollection 사용
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public ICollection<Student> m_listLandSiteDataText { get; set; } protected override void Up(MigrationBuilder migrationBuilder) { migrationBuilder.AddColumn<int>( name: "CourseId", table: "Students", nullable: true); migrationBuilder.CreateIndex( name: "IX_Students_CourseId", table: "Students", column: "CourseId"); migrationBuilder.AddForeignKey( name: "FK_Students_Courses_CourseId", table: "Students", column: "CourseId", principalTable: "Courses", principalColumn: "CourseId", onDelete: ReferentialAction.Restrict); } |
Index와 ForeignKey 없이 생성
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[ForeignKey("Course")] public int CourseId { get; set; } // 또는 [ForeignKey("CourseId")] public int CourseId { get; set; } protected override void Up(MigrationBuilder migrationBuilder) { migrationBuilder.AddColumn<int>( name: "CourseId", table: "Students", nullable: false, defaultValue: 0); } |
virtual 사용시
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public int CourseId { get; set; } [ForeignKey("CourseId")] public virtual Course m_mvLandSiteDataImage { get; set; } protected override void Up(MigrationBuilder migrationBuilder) { migrationBuilder.AddColumn<int>( name: "CourseId", table: "Students", nullable: false, defaultValue: 0); migrationBuilder.CreateIndex( name: "IX_Students_CourseId", table: "Students", column: "CourseId"); migrationBuilder.AddForeignKey( name: "FK_Students_Courses_CourseId", table: "Students", column: "CourseId", principalTable: "Courses", principalColumn: "CourseId", onDelete: ReferentialAction.Cascade); } |
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SqlConnection conn = new SqlConnection(conStr); SqlCommand cmd = new SqlCommand("sp_getdata", conn); cmd.Parameters.Add("@userIndex", SqlDbType.Int).Value = MemberNo; cmd.CommandType = CommandType.StoredProcedure; conn.Open(); SqlDataReader reader = cmd.ExecuteReader(); if (reader.Read()) { Fee = Convert.ToInt32(reader["Fee"].ToString()); } conn.Close(); |
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링크
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