javascript 怎样把拼接起来的<tr><td></td></tr>插入到一个table,

function addcolumns(selecedAllColumns){
var showContentObj=document.getElementById("selectedTableStructShowDiv");
innerHTML.document.getElementById("allColumnsTab");
var userTableStr='';
userTableStr +='<table width="750" height="33" border="1">';
userTableStr += '<tr>';
userTableStr += '<td width="100"><input type="text" size ="11" value=""/></td>';
userTableStr += '<td width="100"><input type="text" value="" size ="11"/></td>';
userTableStr += '<td width="90"><input type="text" value="" size ="8"/></td>';
userTableStr += '<td width="390"><select name="tableColumnsName" id="tableColumnsName" onchange="setDataTypeLength()">';
userTableStr += '<option>--请选择--</option>';
for(var j=0;j<selecedAllColumns.length;j++)
{
var objcolumns = selecedAllColumns[j].columnName+","+selecedAllColumns[j].dataType+","+selecedAllColumns[j].dataLength;
    userTableStr += '<option value="'+objcolumns+'">'+selecedAllColumns[j].columnName+'</option>';
}
userTableStr +='</select></td>';
userTableStr += '<td width="60"><input type="text" value=""/></td>';
userTableStr += '<td width="20"><input type="text" value="" size ="3"/></td>';
userTableStr += '<td width="93"><input id="primaryKey" type="radio" /></td>';
userTableStr += '<td width="93"><input id="defaultValue" type="text" value="" size ="20" /></td>';
userTableStr += '</tr>';
userTableStr +='</table>';


showContentObj.innerHTML=showContentObj.innerHTML+userTableStr;
}
插入到下面的表中要怎么实现
/***
project:uum
author:yangjianting
description:显示所有数据列表的字段信息
updatetime:上午01:11:41
*/
function showSelectTablePage(selecedAllColumns,selectedAllSourceColumns,tableName,sourceTableName,dataSourceTableId)
{
var showContentObj=document.getElementById("selectedTableStructShowDiv");
var userTableStr='';
userTableStr +='
';
userTableStr += '
';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '
';
userTableStr +='
'+sourceTableName+'    '+tableName+'    是否主键    默认值
';
userTableStr +='
';
for(var i=0;i {
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
userTableStr += '';
}
userTableStr +='
'+selectedAllSourceColumns[i].columnName+'    '+selectedAllSourceColumns[i].dataType+'    '+selectedAllSourceColumns[i].dataLength+'    ';
userTableStr += '--请选择--';
for(var j=0;j {
var objcolumns = selecedAllColumns[j].columnName+","+selecedAllColumns[j].dataType+","+selecedAllColumns[j].dataLength;
userTableStr += ''+selecedAllColumns[j].columnName+'';
}
userTableStr +='                  
';
showContentObj.innerHTML="";
showContentObj.innerHTML=userTableStr;
}