Initial code changes to insert/update Ebook records

lib/LocSubject.php

@@ -0,0 +1,43 @@
+<?
+class LocSubject extends Tag{
+	public int $LocSubjectId;
+	public string $Name;
+
+	public function Validate(): void{
+		$error = new Exceptions\ValidationException();
+
+		if(strlen($this->Name) > EBOOKS_MAX_STRING_LENGTH){
+			$error->Add(new Exceptions\StringTooLongException('LoC subject: '. $this->Name));
+		}
+
+		if($error->HasExceptions){
+			throw $error;
+		}
+	}
+
+	public function Create(): void{
+		$this->Validate();
+
+		Db::Query('
+			INSERT into LocSubjects (Name)
+			values (?)
+		', [$this->Name]);
+		$this->LocSubjectId = Db::GetLastInsertedId();
+	}
+
+	public static function GetOrCreate(LocSubject $locSubject): LocSubject{
+		$result = Db::Query('
+				SELECT *
+				from LocSubjects
+				where Name = ?
+			', [$locSubject->Name], 'LocSubject');
+
+		if(isset($result[0])){
+			return $result[0];
+		}
+		else{
+			$locSubject->Create();
+			return $locSubject;
+		}
+	}
+}