Update demo& Add CreateIndex(+4)

Src/Asp.Net/SqlServerTest/Demo/Demo0_SqlSugarClient.cs

@@ -16,7 +16,7 @@ namespace OrmTest
             SqlSugarClient();//Create db
             DbContext();//Optimizing SqlSugarClient usage
             SingletonPattern();//Singleten Pattern
-            //DistributedTransactionExample(); The demo requires three different databases
+            DistributedTransactionExample(); 
             MasterSlave();//Read-write separation 
             CustomAttribute(); 
         }
@@ -229,7 +229,7 @@ namespace OrmTest
                 new ConnectionConfig(){ ConfigId="1", DbType=DbType.SqlServer, ConnectionString=Config.ConnectionString,InitKeyType=InitKeyType.Attribute,IsAutoCloseConnection=true },
                 new ConnectionConfig(){ ConfigId="2", DbType=DbType.SqlServer, ConnectionString=Config.ConnectionString2 ,InitKeyType=InitKeyType.Attribute ,IsAutoCloseConnection=true}
             });
-
+            var db1 = db.Ado.Connection.Database;
             //use db1
             db.CodeFirst.SetStringDefaultLength(200).InitTables(typeof(Order), typeof(OrderItem));//
             db.Insertable(new Order() { Name = "order1", CreateTime = DateTime.Now }).ExecuteCommand();
@@ -237,11 +237,16 @@ namespace OrmTest
 
             //use db2
             db.ChangeDatabase("2");
+            var db2 = db.Ado.Connection.Database;
             db.DbMaintenance.CreateDatabase();//Create Database2
             db.CodeFirst.SetStringDefaultLength(200).InitTables(typeof(Order), typeof(OrderItem));
             db.Insertable(new Order() { Name = "order1", CreateTime = DateTime.Now }).ExecuteCommand();
             Console.WriteLine(db.CurrentConnectionConfig.DbType + ":" + db.Queryable<Order>().Count());
 
+            if (db2 == db1) 
+            {
+                return;
+            }
             // Example 1
             Console.WriteLine("Example 1");
             try

Src/Asp.Net/SqlSugar/Abstract/DbMaintenanceProvider/Methods.cs

@@ -325,6 +325,12 @@ namespace SqlSugar
             this.Context.Ado.ExecuteCommand(sql);
             return true;
         }
+        public virtual bool CreateIndex(string tableName, string[] columnNames, string IndexName, bool isUnique = false) 
+        {
+            string sql = string.Format("CREATE {3} INDEX {2} ON {0}({1})", tableName, string.Join(",", columnNames), IndexName, isUnique ? "UNIQUE" : "");
+            this.Context.Ado.ExecuteCommand(sql);
+            return true;
+        }
         public virtual bool IsAnyIndex(string indexName)
         {
             string sql = string.Format(this.IsAnyIndexSql, indexName);

Src/Asp.Net/SqlSugar/Interface/IDbMaintenance.cs

@@ -29,6 +29,7 @@ namespace SqlSugar
         #region DDL
         bool AddDefaultValue(string tableName,string columnName,string defaultValue);
         bool CreateIndex(string tableName, string [] columnNames, bool isUnique=false);
+        bool CreateIndex(string tableName, string[] columnNames, string IndexName, bool isUnique = false);
         bool DropTable(string tableName);
         bool TruncateTable(string tableName);
         bool TruncateTable<T>();