A layer on top of Umbraco's MigrationBase for checking a table has Indexes, Constraints & Columns

CustomMigrationBase.cs

using System.Linq;
using Umbraco.Core.Logging;
using Umbraco.Core.Persistence.Migrations;
using Umbraco.Core.Persistence.SqlSyntax;

namespace My.Website.Migrations
{
    public abstract class CustomMigrationBase : MigrationBase
    {
        public CustomMigrationBase(ISqlSyntaxProvider sqlSyntax, ILogger logger) : base(sqlSyntax, logger)
        {
        }

        protected bool CheckTableAlreadyHasIndex(string tableName, string indexName)
        {

            var indexes = SqlSyntax.GetDefinedIndexes(Context.Database);

            /*
             * Returns
             * 
             * Tuple<string, string, string, bool>
             * 
             * Item1: table name
             * Item2: index name
             * Item3: column name
             * Item4: unique
             * 
             * A multi-column index has multiple records returned from this function
             * 
             */

            return indexes.Any(x => 
                                string.Equals(x.Item1, tableName) &&
                                string.Equals(x.Item2, indexName)
                   );
        }

        protected bool CheckTableAlreadyHasColumn(string tableName, string columnName)
        {
            var columns = SqlSyntax.GetColumnsInSchema(Context.Database);
            var doesColumnExist =
                columns.Any(
                    x =>
                        string.Equals(x.TableName, tableName) &&
                        string.Equals(x.ColumnName, columnName)
                );

            return doesColumnExist;
        }


        protected bool CheckTableAlreadyHasConstraint(string tableName, string constraintName)
        {
            var constraints = SqlSyntax.GetConstraintsPerTable(Context.Database);

            return constraints.Any(x => string.Equals(tableName, x.Item1) 
                                     && string.Equals(constraintName, x.Item2));

        }
    }
}

UsageOfCustomMigrationBase.cs

using SmartCentre.Web.Umbraco.Core.Extensions;
using System;
using Umbraco.Core.Logging;
using Umbraco.Core.Persistence.Migrations;
using Umbraco.Core.Persistence.SqlSyntax;

namespace My.Website.Migrations
{
    [Migration("1.0.0", 0, "ProductsName")]
    public class UsageOfCustomMigrationBase : CustomMigrationBase
    {
        public UsersMigration(ISqlSyntaxProvider sqlSyntax, ILogger logger) : base(sqlSyntax, logger)
        {
        }

        public override void Down()
        {
            throw new NotImplementedException();
        }

        public override void Up()
        {
            AddColumns();
            AddIndexes();
        }

        private void AddIndexes()
        {
            if (CheckTableAlreadyHasIndex("tableName", "indexName"))
            {
                // Log you're skipping this
            }
            else
            {
                Create.Index("indexName").OnTable("tableName").OnColumn("columnName").Ascending()
                                                 .WithOptions().NonClustered()
                                                 .WithOptions().Unique();
            }
        }

        private void AddColumns()
        {
            if (CheckTableAlreadyHasColumn("tableName", "columnName"))
            {
                // Log skipping column
            }
            else
            {
                Alter.Table("tableName").AddColumn("columnName").AsInt32().Nullable();
            }
        }
    }
}