feat(db): Add PostgreSQL query creator implementation

Implements a query creator for PostgreSQL, allowing for proper database type mapping and table creation functionalities.

Enhances the library's database support by incorporating PostgreSQL-specific features such as SERIAL/BIGSERIAL for auto-increment columns and improved escape handling for table names.

Improves the extensibility and compatibility of the database framework with different SQL databases.

TShockAPI/DB/Queries/PostgresQueryCreator.cs

@@ -0,0 +1,89 @@
+/*
+TShock, a server mod for Terraria
+Copyright (C) 2011-2019 Pryaxis & TShock Contributors
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using MySql.Data.MySqlClient;
+
+namespace TShockAPI.DB.Queries;
+
+/// <summary>
+/// Query Creator for PostgreSQL
+/// </summary>
+public class PostgresQueryCreator : GenericQueryCreator
+{
+	/// <inheritdoc />
+	public override string DbTypeToString(MySqlDbType type, int? length) => type switch
+	{
+		MySqlDbType.VarChar when length is not null => "VARCHAR({0})".SFormat(length),
+		MySqlDbType.String when length is not null => "CHAR({0})".SFormat(length),
+		MySqlDbType.Text => "TEXT",
+		MySqlDbType.TinyText => "TEXT",
+		MySqlDbType.MediumText => "TEXT",
+		MySqlDbType.LongText => "TEXT",
+		MySqlDbType.Float => "REAL",
+		MySqlDbType.Double => "DOUBLE PRECISION",
+		MySqlDbType.Int32 => "INT",
+		MySqlDbType.Int64 => "BIGINT",
+		MySqlDbType.DateTime => "TIMESTAMP",
+
+		_ => throw new NotImplementedException(Enum.GetName(typeof(MySqlDbType), type))
+	};
+
+	/// <inheritdoc />
+	protected override string EscapeTableName(string table) => table.SFormat("\"{0}\"", table);
+
+	/// <inheritdoc />
+	public override string CreateTable(SqlTable table)
+	{
+		ValidateSqlColumnType(table.Columns);
+
+		IEnumerable<string> columns = table.Columns.Select(c =>
+		{
+			// Handle PostgreSQL-specific auto-increment using SERIAL/BIGSERIAL
+			string dataType;
+
+			if (c.AutoIncrement)
+			{
+				dataType = c.Type is MySqlDbType.Int32 ? "SERIAL" : "BIGSERIAL";
+			}
+			else
+			{
+				dataType = DbTypeToString(c.Type, c.Length);
+			}
+
+			return "\"{0}\" {1} {2} {3} {4}".SFormat(c.Name,
+				dataType,
+				c.Primary ? "PRIMARY KEY" : "",
+				c.NotNull && !c.AutoIncrement ? "NOT NULL" : "", // SERIAL implies NOT NULL
+				c.DefaultCurrentTimestamp ? "DEFAULT CURRENT_TIMESTAMP" : "");
+		});
+
+		string[] uniques = table.Columns
+			.Where(c => c.Unique).Select(c => $"\"{c.Name}\"")
+			.ToArray(); // No re-enumeration
+
+		return "CREATE TABLE {0} ({1} {2})".SFormat(EscapeTableName(table.Name),
+			string.Join(", ", columns),
+			uniques.Any() ? ", UNIQUE({0})".SFormat(string.Join(", ", uniques)) : "");
+	}
+
+	/// <inheritdoc />
+	public override string RenameTable(string from, string to) => /*lang=postgresql*/"ALTER TABLE {0} RENAME TO {1}".SFormat(from, to);
+}