Added QueryBuilder

> Added build for SelectByPrimaryKey/s
Added Attributes
Added Function
> SqlSerialise and escape

Database-Attribute_System/Attributes/DbAttribute.cs

@@ -0,0 +1,22 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
+{
+    [AttributeUsage(AttributeTargets.Field, Inherited = false, AllowMultiple = false)]
+    public class DbAttribute : Attribute
+    {
+        public string _attributeName;
+
+        /// <summary>
+        /// Marks variable as database-attribute
+        /// </summary>
+        /// <param name="dbAttributeName">Name of database-attribute (case-sensitivity is determined from database-attribute-settings) ['null' if the same as field-name]</param>
+        public DbAttribute(string attributeName =  null)
+        {
+            this._attributeName = attributeName;
+        }
+    }
+}

Database-Attribute_System/Attributes/DbForeignKey.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
+{
+    [AttributeUsage(AttributeTargets.Field, Inherited = false, AllowMultiple = false)]
+    public class DbForeignKey : Attribute
+    {
+        public Type _classType;
+        public string _attributeName;
+
+        /// <summary>
+        /// Marks variable as foreignKey of given class
+        /// </summary>
+        /// <param name="classType">Type of class to which this is the ForeignKey</param>
+        /// <param name="dbAttributeName">Name of database-attribute (case-sensitivity is determined from database-attribute-settings) ['null' if the same as field-name]</param>
+        public DbForeignKey(Type classType, string attributeName = null)
+        {
+            this._classType = classType;
+            this._attributeName = attributeName;
+        }
+    }
+}

Database-Attribute_System/Attributes/DbObject.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Reflection;
+using System.Threading.Tasks;
+
+namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
+{
+    [AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]
+    public class DbObject : Attribute
+    {
+        public string _tableName;
+
+        /// <summary>
+        /// Marks variable as database-table
+        /// </summary>
+        /// <param name="tableName">Name of database-table (case-sensitivity is determined from database-table-settings) ['null' if the same as class-name]</param>
+        public DbObject(string tableName = null)
+        {
+            this._tableName = tableName;
+        }
+    }
+}

Database-Attribute_System/Attributes/DbPrimaryKey.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace eu.railduction.netcore.dll.Database_Attribute_System.Attributes
+{
+    [AttributeUsage(AttributeTargets.Field, Inherited = false, AllowMultiple = false)]
+    public class DbPrimaryKey : Attribute
+    {
+        public Type _classType;
+        public string _attributeName;
+
+        /// <summary>
+        /// Marks variable as primaryKey fo current class
+        /// </summary>
+        /// <param name="dbAttributeName">Name of database-attribute (case-sensitivity is determined from database-attribute-settings) ['null' if the same as field-name]</param>
+        public DbPrimaryKey(string attributeName = null)
+        {
+            this._attributeName = attributeName;
+        }
+    }
+}

Database-Attribute_System/Class1.cs

@@ -1,8 +0,0 @@
-using System;
-
-namespace eu.railduction.netcore.dll.Database_Attribute_System
-{
-    public class Class1
-    {
-    }
-}

Database-Attribute_System/Function.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace eu.railduction.netcore.dll.Database_Attribute_System
+{
+    class Function
+    {
+        public static string SqlEscape(string str)
+        {
+            string str_cpy = str.Replace(@"'", @"\'");
+            return str_cpy;
+        }
+
+        public static string SqlSerialise(DateTime dt)
+        {
+            return dt.ToString("yyyy-MM-dd HH:mm:ss");
+        }
+    }
+}

Database-Attribute_System/QueryBuilder.cs

@@ -0,0 +1,115 @@
+using eu.railduction.netcore.dll.Database_Attribute_System.Attributes;
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace eu.railduction.netcore.dll.Database_Attribute_System
+{
+    public class QueryBuilder
+    {
+        /// <summary>
+        /// Build an SELECT-SQL-query by a database-primary-key<pragma/>
+        /// Will build the query-string based on the <paramref name="comparisonValue"/> including serialising and escaping for SQL.<para/>
+        /// </summary>
+        /// <param name="handler">Method to send querys to the database</param>
+        /// <param name="primaryKey">Database comparison value</param>
+        /// <returns>Built SQL-Query</returns>
+        public static string SelectByPrimaryKey(Type classType, object comparisonValue) => SelectByPrimaryKeys(classType, comparisonValue);
+        /// <summary>
+        /// Build an SELECT-SQL-query by database-primary-keys<pragma/>
+        /// Will build the query-string based on the <paramref name="comparisonValues"/> including serialising and escaping for SQL.<para/>
+        /// </summary>
+        /// <param name="handler">Method to send querys to the database</param>
+        /// <param name="primaryKeys">Database comparison values (Must be the exact same amount as primary keys in class/table)</param>
+        /// <returns>Built SQL-Query</returns>
+        public static string SelectByPrimaryKeys(Type classType, params object[] comparisonValues)
+        {
+            // Check if class has attribute 'DbObject' and get the database table-name
+            DbObject dbObjectAttribute = classType.GetCustomAttribute(typeof(DbObject), true) as DbObject;
+            if (dbObjectAttribute == null) throw new InvalidOperationException("Cannot generate SQL-Query of class. Missing Attribute 'DbObject'");
+            string tableName = dbObjectAttribute._tableName ?? dbObjectAttribute._tableName;    // If no alternative table-name is specified, use the class-name
+
+            // Iterate thru all properties
+            List<string> dbPrimaryKeys = new List<string>() { };
+            foreach (System.Reflection.PropertyInfo pi in classType.GetProperties())
+            {
+                // Get primaryKey attribute from current property
+                DbPrimaryKey pkey = pi.GetCustomAttribute(typeof(DbPrimaryKey) ,true) as DbPrimaryKey;
+                if(pkey != null)
+                {
+                    string dbAttributeName = pkey._attributeName ?? pi.Name;     // If no alternative attribute-name is specified, use the property-name
+                    dbPrimaryKeys.Add(dbAttributeName);
+                }
+            }
+
+            if (comparisonValues.Length != dbPrimaryKeys.Count)
+                throw new InvalidOperationException("Primary-key number of class/table and number of comparison values is not equal!");
+
+            object[] whereParams = new object[comparisonValues.Length*2];
+            for (int i=0,c=0; c<whereParams.Length; i++,c+=2)
+            {
+                string sql_string = "";
+
+                if (i > 0) sql_string += " AND ";
+                sql_string += $"{dbPrimaryKeys[i]}=";
+
+                whereParams[c] = sql_string;
+                whereParams[c+1] = comparisonValues[i];
+            }
+
+            return BuildQuery($"SELECT * FROM {tableName} WHERE ", whereParams);
+        }
+
+
+        /// <summary>
+        /// Build an SQL-query<para/>
+        /// Will build the query-string based on the <paramref name="param"/>s including serialising and escaping for SQL.<para/>
+        /// </summary>
+        /// <param name="param">Params with alternating query-parts and objects beginning with a query-part
+        /// <para/>Example: "SELECT * FROM table WHERE id=", id, " AND name=", name</param>
+        public static string BuildQuery(params object[] param)
+        {
+            string query = "";
+            for (int i = 0; i < param.Length; i++)
+            {
+                if (i % 2 == 0) query += param[i];  // Every 'even' count will just add
+                else       // Every 'uneven' count will handle param as passed variable    
+                {
+                    string paramString = "";
+                    if (param[i] == null)            // Handle null
+                    {
+                        paramString = "null";
+                    }
+                    else if (param[i].GetType() == typeof(string))       // Handle strings
+                    {
+                        paramString = "'" + Function.SqlEscape((string)param[i]) + "'";  // wrap in sql-brackets and escape sql, if any
+                    }
+                    else if (param[i].GetType() == typeof(int) || param[i].GetType() == typeof(float) || param[i].GetType() == typeof(double))  // Handle int, float & double
+                    {
+                        paramString = param[i].ToString().Replace(",", ".");    // just format to string and form comma to sql-comma
+                    }
+                    else if (param[i].GetType() == typeof(DateTime))        // Handle DateTime
+                    {
+                        DateTime dateTime = (DateTime)param[i];
+                        paramString = "'" + Function.SqlSerialise(dateTime) + "'";     // wrap in sql-brackets and convert to sql-datetime
+                    }
+                    else if (param[i].GetType() == typeof(Guid))        // Handle DateTime
+                    {
+                        string guid = ((Guid)param[i]).ToString();  // Get Guid as string
+                        paramString = "'" + guid + "'";                 // wrap in sql-brackets
+                    }
+                    else        // Unknown type in params
+                    {
+                        throw new Exception($"Error in query-builder: Type '{param.GetType().ToString()}' cannot be used!");
+                    }
+
+                    // Add formed param to query
+                    query += paramString;
+                }
+            }
+
+            // return built query
+            return query;
+        }
+    }
+}