Finished:

-sqlite altering
-implemented mysql
Todo:
-Merge SqlTableCreator into the querybuilders or make it static
-Make all the managers use the querybuilder for making tables. (See GroupManager.cs for an example)
-Implement more datatypes (see TypesAsStrings in IQueryBuilder.cs)

TShockAPI/DB/GroupManager.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Data;
 using System.IO;
 using System.Linq;
+using MySql.Data.MySqlClient;
 
 namespace TShockAPI.DB
 {
@@ -18,13 +19,13 @@ namespace TShockAPI.DB
 
             string query = "";
 
-            var table = new SqlTable("GroupList",
+            /*var table = new SqlTable("GroupList",
-                new SqlColumn("GroupName", "TEXT") { Primary = true },
+                new SqlColumn("GroupName", MySqlDbType.VarChar, 32) { Primary = true },
-                new SqlColumn("Commands", "TEXT"),
+                new SqlColumn("Commands", MySqlDbType.Text),
-                new SqlColumn("ChatColor", "TEXT")
+                new SqlColumn("ChatColor", MySqlDbType.Text)
             );
 
-            //new SqlTableCreator(db).EnsureExists(table);
+            new SqlTableCreator(db, new MysqlQueryCreator()).EnsureExists(table);*/
 
 
             if (db.GetSqlType() == SqlType.Sqlite)

TShockAPI/DB/IQueryBuilder.cs

@@ -1,7 +1,9 @@
 using System;
 using System.Collections.Generic;
+using System.Data;
 using System.Linq;
 using System.Text;
+using MySql.Data.MySqlClient;
 using TShockAPI.Extensions;
 
 namespace TShockAPI.DB
@@ -10,19 +12,33 @@ namespace TShockAPI.DB
     {
         string CreateTable(SqlTable table);
         string AlterTable(SqlTable from, SqlTable to);
+        string DbTypeToString(MySqlDbType type, int? length);
     }
 
     public class SqliteQueryCreator : IQueryBuilder
     {
         public string CreateTable(SqlTable table)
         {
-            var columns = table.Columns.Select(c => "'{0}' {1} {2} {3} {4}".SFormat(c.Name, c.Type, c.Primary ? "PRIMARY KEY" : "", c.AutoIncrement ? "AUTOINCREMENT" : "", c.NotNull ? "NOT NULL" : "", c.Unique ? "UNIQUE" : ""));
+            var columns = table.Columns.Select(c => "'{0}' {1} {2} {3} {4}".SFormat(c.Name, DbTypeToString(c.Type, c.Length), c.Primary ? "PRIMARY KEY" : "", c.AutoIncrement ? "AUTOINCREMENT" : "", c.NotNull ? "NOT NULL" : "", c.Unique ? "UNIQUE" : ""));
             return "CREATE TABLE '{0}' ({1})".SFormat(table.Name, string.Join(", ", columns));
         }
         static Random rand = new Random();
+        /// <summary>
+        /// Alter a table from source to destination
+        /// </summary>
+        /// <param name="from">Must have name and column names. Column types are not required</param>
+        /// <param name="to">Must have column names and column types.</param>
+        /// <returns></returns>
         public string AlterTable(SqlTable from, SqlTable to)
         {
-            return "";
+            var rstr = rand.NextString(20);
+            var alter = "ALTER TABLE '{0}' RENAME TO '{1}_{0}'".SFormat(from.Name, rstr);
+            var create = CreateTable(to);
+            //combine all columns in the 'from' variable excluding ones that aren't in the 'to' variable.
+            //exclude the ones that aren't in 'to' variable because if the column is deleted, why try to import the data?
+            var insert = "INSERT INTO '{0}' ({1}) SELECT {1} FROM {2}_{0}".SFormat(from.Name, string.Join(", ", from.Columns.Where(c => to.Columns.Any(c2 => c2.Name == c.Name)).Select(c => c.Name)), rstr);
+            var drop = "DROP TABLE '{0}_{1}'".SFormat(rstr, from.Name);
+            return "{0}; {1}; {2}; {3};".SFormat(alter, create, insert, drop);
             /*
                 ALTER TABLE "main"."Bans" RENAME TO "oXHFcGcd04oXHFcGcd04_Bans"
                 CREATE TABLE "main"."Bans" ("IP" TEXT PRIMARY KEY ,"Name" TEXT)
@@ -30,18 +46,68 @@ namespace TShockAPI.DB
                 DROP TABLE "main"."oXHFcGcd04oXHFcGcd04_Bans"
              */
         }
+
+
+        static readonly Dictionary<MySqlDbType, string> TypesAsStrings = new Dictionary<MySqlDbType, string>
+        {
+            {MySqlDbType.VarChar, "TEXT"},
+            {MySqlDbType.String, "TEXT"},
+            {MySqlDbType.Text, "TEXT"},
+            {MySqlDbType.TinyText, "TEXT"},
+            {MySqlDbType.MediumText, "TEXT"},
+            {MySqlDbType.LongText, "TEXT"},
+        };
+        public string DbTypeToString(MySqlDbType type, int? length)
+        {
+            string ret;
+            if (TypesAsStrings.TryGetValue(type, out ret))
+                return ret;
+            throw new NotImplementedException(Enum.GetName(typeof(MySqlDbType), type));
+        }
     }
     public class MysqlQueryCreator : IQueryBuilder
     {
         public string CreateTable(SqlTable table)
         {
-            throw new NotImplementedException();
+            var columns = table.Columns.Select(c => "{0} {1} {2} {3}".SFormat(c.Name, DbTypeToString(c.Type, c.Length), c.Primary ? "PRIMARY KEY" : "", c.AutoIncrement ? "AUTOINCREMENT" : "", c.NotNull ? "NOT NULL" : ""));
+            var uniques = table.Columns.Where(c => c.Unique).Select(c => c.Name);
+            return "CREATE TABLE {0} ({1}) {2}".SFormat(table.Name, string.Join(", ", columns), uniques.Count() > 0 ? ", UNIQUE({0})".SFormat(string.Join(", ", uniques)) : "");
+        }
+        static Random rand = new Random();
+        /// <summary>
+        /// Alter a table from source to destination
+        /// </summary>
+        /// <param name="from">Must have name and column names. Column types are not required</param>
+        /// <param name="to">Must have column names and column types.</param>
+        /// <returns></returns>
+        public string AlterTable(SqlTable from, SqlTable to)
+        {
+            var rstr = rand.NextString(20);
+            var alter = "RENAME TABLE {0} TO {1}_{0}".SFormat(from.Name, rstr);
+            var create = CreateTable(to);
+            //combine all columns in the 'from' variable excluding ones that aren't in the 'to' variable.
+            //exclude the ones that aren't in 'to' variable because if the column is deleted, why try to import the data?
+            var insert = "INSERT INTO {0} ({1}) SELECT {1} FROM {2}_{0}".SFormat(from.Name, string.Join(", ", from.Columns.Where(c => to.Columns.Any(c2 => c2.Name == c.Name)).Select(c => c.Name)), rstr);
+            var drop = "DROP TABLE {0}_{1}".SFormat(rstr, from.Name);
+            return "{0}; {1}; {2}; {3};".SFormat(alter, create, insert, drop);
         }
 
 
-        public string AlterTable(SqlTable from, SqlTable to)
+        static readonly Dictionary<MySqlDbType, string> TypesAsStrings = new Dictionary<MySqlDbType, string>
         {            
-            throw new NotImplementedException();
+            {MySqlDbType.VarChar, "VARCHAR"},
+            {MySqlDbType.String, "CHAR"},
+            {MySqlDbType.Text, "TEXT"},
+            {MySqlDbType.TinyText, "TINYTEXT"},
+            {MySqlDbType.MediumText, "MEDIUMTEXT"},
+            {MySqlDbType.LongText, "LONGTEXT"},
+        };
+        public string DbTypeToString(MySqlDbType type, int? length)
+        {
+            string ret;
+            if (TypesAsStrings.TryGetValue(type, out ret))
+                return ret + (length != null ? "({0})".SFormat((int)length) : "");
+            throw new NotImplementedException(Enum.GetName(typeof(MySqlDbType), type));
         }
     }
 }

TShockAPI/DB/SqlColumn.cs

@@ -1,7 +1,4 @@
-using System;
+using MySql.Data.MySqlClient;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace TShockAPI.DB
 {
@@ -9,7 +6,8 @@ namespace TShockAPI.DB
     {
         //Required
         public string Name { get; set; }
-        public string Type { get; set; }
+        public MySqlDbType Type { get; set; }
+
 
         //Optional
         public bool Unique { get; set; }
@@ -18,10 +16,20 @@ namespace TShockAPI.DB
         public bool NotNull { get; set; }
         public string DefaultValue { get; set; }
 
-        public SqlColumn(string name, string type)
+        /// <summary>
+        /// Length of the data type, null = default
+        /// </summary>
+        public int? Length { get; set; }
+
+        public SqlColumn(string name, MySqlDbType type)
+            : this(name, type, null)
+        {
+        }
+        public SqlColumn(string name, MySqlDbType type, int? length)
         {
             Name = name;
             Type = type;
+            Length = length;
         }
     }
 }

TShockAPI/DB/SqlTable.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Data;
 using System.Linq;
 using System.Text;
+using MySql.Data.MySqlClient;
 
 namespace TShockAPI.DB
 {
@@ -36,9 +37,10 @@ namespace TShockAPI.DB
             var columns = GetColumns(table);
             if (columns.Count > 0)
             {
-                if (table.Columns.All(c => columns.Contains(c.Name)))
+                if (!table.Columns.All(c => columns.Contains(c.Name)) || !columns.All(c => table.Columns.Any(c2 => c2.Name == c)))
                 {
-                    
+                    var from = new SqlTable(table.Name, columns.Select(s => new SqlColumn(s, MySqlDbType.String)).ToList());
+                    database.Query(creator.AlterTable(from, table));
                 }
             }
             else
@@ -61,7 +63,11 @@ namespace TShockAPI.DB
             }
             else if (name == SqlType.Mysql)
             {
-                throw new NotImplementedException();
+                using (var reader = database.QueryReader("SELECT COLUMN_NAME FROM information_schema.COLUMNS WHERE TABLE_NAME=@0 AND TABLE_SCHEMA=@1", table.Name, database.Database))
+                {
+                    while (reader.Read())
+                        ret.Add(reader.Get<string>("COLUMN_NAME"));
+                }
             }
             else
             {

TShockAPI/Extensions/DbExt.cs

@@ -71,7 +71,7 @@ namespace TShockAPI.DB
             var name = conn.GetType().Name;
             if (name == "SqliteConnection")
                 return SqlType.Sqlite;
-            if (name == "MysqlConnection")
+            if (name == "MySqlConnection")
                 return SqlType.Mysql;
             return SqlType.Unknown;
         }