同时从两个 SQL 语句查询？

Question

我有两个 SQL 查询：第一个查询从数据库中提取所有 criteria，第二个查询查找任何 criteria completed：

SQL 查询 1

//get all criteria for section
$getcrit = $mysqli->prepare("SELECT id, category_id, section_name, criteria  
FROM prepare_criteria
WHERE category_id=? AND section_name=? ");
$getcrit->bind_param('is', $cat_id, $sectname);
$getcrit->bind_result($criteria_id, $category_id, $section_name, $criteria);
$getcrit->execute();
$getcrit->store_result();
$row_cnt = $getcrit->num_rows();
$getcrit->fetch();

SQL 查询 2

//get any checked criteria from db
$getcompcrit = $mysqli->prepare("SELECT prepare_criteria_complete.criteria_id, prepare_criteria.id, prepare_criteria.criteria, prepare_criteria_complete.business_id, prepare_criteria_complete.category_id 
FROM prepare_criteria_complete, prepare_criteria
WHERE business_id=?
AND prepare_criteria.id=prepare_criteria_complete.criteria_id");
$getcompcrit->bind_param('i', $business_id);
$getcompcrit->bind_result($cc_criteria_id, $criteria_completed_id, $comp_criteria, $business_id_db, $category_db);
$getcompcrit->execute();
$getcompcrit->store_result();
$gc_row_cnt = $getcompcrit->num_rows();

然后我正在编写一个while 循环来检查任何criteria completed：

if ($gc_row_cnt >=1)
{
    while ($getcompcrit->fetch() )
    {
        if ($cc_criteria_id==$criteria_completed_id)
        {
            echo $criteria_completed_id." ";    
        }
        if ($criteria_id!=$criteria_completed_id) 
        {
        echo $criteria_id." ";  
        }
    }
}

第二个if 未按预期运行。 我知道必须有一种更清洁的方法来做到这一点！ 也许是JOIN 声明？

Answer 1

当然可以使用下一个查询：

SELECT 
    pc.id, pc.criteria,
    coalesce(pcc.business_id, 'not complete') business_id,
    coalesce(pcc.category_id, 'not complete') category_id
FROM prepare_criteria pc
LEFT JOIN prepare_criteria_complete pcc 
    ON pc.id=pcc.criteria_id AND pcc.business_id=?;

如果prepare_criteria 记录与prepare_criteria_complete 表中的记录不匹配，则查询使用coalesce 运算符返回“不完整”字符串。

Answer 2

SQL 查询

$qry = $mysqli->prepare("
SELECT 
    pc.id, pc.criteria, pc.category_id,
    coalesce(pcc.business_id, 'N') business_id
FROM prepare_criteria pc
LEFT JOIN prepare_criteria_complete pcc 
    ON pc.id=pcc.criteria_id 
    WHERE pc.category_id=? ");
$qry->bind_param('i', $cat_id);
$qry->bind_result($qry_id, $qry_criteria, $qry_cat_id, $qry_bus_id );
$qry->execute();
$qry->store_result();
$qry_row_cnt = $qry->num_rows();

PHP

if ($qry_row_cnt >=1)
                            {
                                while ($qry->fetch() )
                                {               
                                    if( ($qry_bus_id==$business_id) )
                                    {
                                    //criteria is checked
                                    }
                                    else
                                    {
                                    //criteria not checked
                                    }   
                                }
                            }