/// <summary>
/// 添加到GroupBy子句
/// </summary>
/// <param name="builder">Sql生成器</param>
/// <param name="sql">Sql语句</param>
/// <param name="condition">该值为true时添加Sql，否则忽略</param>
public static ISqlBuilder AppendGroupBy(this ISqlBuilder builder, string sql, bool condition)
{
if (condition)
{
builder.AppendGroupBy(sql);
}
return(builder);
}