How to modify getselectstatement to get inner join select statement ?

select FooterTable.ItemCode,FooterTable.Quantity,FooterTable.UniPrice from

MasterTable inner join FooterTable on MasterTable.Serial=FooterTable.Serial,MasterTable.BranchCode=FooterTable.BranchCode,MasterTable.Year=FooterTable.Year

where MasterTable.Serial=10 AND MasterTable.Year=2019 AND MasterTable.BranchCode=1

{ 
   "Details":{ 
      "table":[ 
         "MasterTable",
         "FooterTable"
      ],
      "fields":{ 
         "ItemCode":"string",
         "Quantity":"int",
         "Price":"decimal"
         
      },
      "keys":{ 
         "BranchCode":1,
         "Year":2019,
         "Serial":2
      }
   }
}

public string GetSelectStatement(string JsonDataForSelect)
{
var root = (JObject)JsonConvert.DeserializeObject(JsonDataForSelect);
var query = "";
var items = root.SelectToken("Details").Children().OfType<JProperty>().ToDictionary(p => p.Name, p => p.Value);
foreach (var item in items)
{
if (item.Key == "table")
{
var tableName = item.Value;
query = string.Format("select from table {0} inner join table{1} where", tableName);
}
else if (item.Key == "keys")
{
var key = item.Value.SelectToken("").OfType<JProperty>().ToDictionary(p => p.Name, p => p.Value);
var count = 0;
foreach (var id in key)
{
count++;
if (count == key.Count())
{
query += string.Format("{0} = {1}", id.Key, id.Value);
}
else
{
query += string.Format("{0} = {1} and ", id.Key, id.Value);
}
}

}
}
return query;
}