sql - 从 sql 解析器中提取订单类型

Question

用于 global sql parser (gsp)从 order sql 查询中提取列和排序类型，并从 where 条件中提取和或

SELECT employee_id, dept, name, age, salary
FROM employee_info
WHERE dept = 'Sales' and ID=1
ORDER BY salary, age DESC,ID;

我可以提取列名，但可以提取订单类型

1-如何提取订单类型？

2-如何提取和，或从哪里sql？

Answer 1

如果pSqlstmt是gsp_selectStatement * 那么你可以这样做：

if(pSqlstmt->orderbyClause != nullptr)
{       
    string sortType;
    int colNumOrderBy = pSqlstmt->orderbyClause->items->length;

    for(int i = 0; i < colNumOrderBy; i++)
    {
        gsp_orderByItem *field = reinterpret_cast<gsp_orderByItem *>(gsp_list_celldata(pSqlstmt->orderbyClause->items->head));

        //get order by column name
        char *sortCol = gsp_node_text(reinterpret_cast<gsp_node*>(field->sortKey)); 

        if(field->sortToken== nullptr)
        {
            //ERROR
        }
        else
        {
            //find out sorting type (ASC/DESC)
            sortType = sortType.substr(0,field->sortToken->nStrLen);
        }

        free(sortCol);
        pSqlstmt->orderbyClause->items->head = pSqlstmt->orderbyClause->items->head->nextCell;
    }

}