Question

对于所有关心的人，我发现我需要重新阅读有关查询的基础知识。排序后，我意识到我的代码中存在一些错误。

我有一个我正在尝试构建的查询，并且在出现关于歧义的错误之后我会抛出错误。有人会告诉我如何正确执行MySQL别名吗？

到目前为止，这是我的代码。它工作正常，直到我把连接放在那里。我怀疑这是因为我在同一个查询中不止一次引用'wine'，但这可能是许多问题之一。

$query = 
"SELECT 
    wine_id, 
    wine_name, 
    winery_name, 
    region_name, 
    year, 
    variety
FROM 
    wine AS w, 
    winery, 
    region, 
    grape_variety
JOIN 
    wine 
ON
    grape_variety.variety_id = wine.wine_id
JOIN 
    wine_variety 
ON
    wine.wine_id = wine_variety.variety_id
WHERE 
    winery.region_id = region.region_id
AND 
    wine.winery_id = winery.winery_id"; 

if (!empty($wineName)) {
    $query .= " AND wine_name = '{$wineName}'";
}

if (!empty($wineryName)) {
    $query .= " AND winery_name = '{$wineryName}'";
}

// If the user has specified a region, add the regionName 
// as an AND clause
if (isset($regionName) && $regionName != "All") {
    $query .= " AND region_name = '{$regionName}'"; 
} 

// If the user has specified a variety, add the grapeVariety 
// as an AND clause
if (isset($grapeVariety) && $grapeVariety != "Riesling") {
    $query .= " AND variety = '{$grapeVariety}'"; 
}

Answer 1

尝试这样做：

SELECT w.wine_id, w.wine_name,  winery_name, region_name,  year, variety
FROM 
    wine AS w 
    join winery on w.winery_id = winery.winery_id
    join region on winery.region_id = region.region_id, 
    join grape_variety on grape_variety.variety_id = w.wine_id

Answer 2

您的查询必须如下：

SELECT 
    w.wine_id, 
    w.wine_name, 
    wy.winery_name,-- I assume this column from table `wy` 
    r.region_name, -- column from table `region` 
    w.year, 
    w.variety
FROM wine w 
INNER JOIN winery wy ON (wy.winery_id = w.winery_id )
INNER JOIN region r ON ( r.region_id = wy.region_id )
INNER JOIN  grape_variety gv ON (gv.variety_id = w.wine_id)
INNER JOIN  wine_variety wv ON  (wv.variety_id = w.wine_id)
...
append other WHERE conditions here

注意：如果你给表结构然后它会更清楚，首先我假设你检索的任何列是来自主表和如果查询中的所有表都具有相同的列名，则使用table_alias_name.column_name。

Answer 3

试试这个

SELECT 
    w.wine_id, 
    w.wine_name, 
    wy.winery_name, 
    r.region_name, 
    r.year, 
    wv.variety
FROM wine w 
INNER JOIN winery wy ON (wy.winery_id = w.winery_id )
INNER JOIN region r ON ( r.region_id = wy.region_id )
INNER JOIN  grape_variety gv ON (gv.variety_id = w.wine_id)
INNER JOIN  wine_variety wv ON  (wv.variety_id = w.wine_id)

Answer 4

使用此

$query = 
 "SELECT 
   w.wine_id, 
   w.wine_name, 
   winery.winery_name, 
   region.region_name, 
   year, 
   grape_variety.variety
FROM 
   wine AS w, 
   winery, 
   region, 
   grape_variety
JOIN 
   wine 
ON
   grape_variety.variety_id = wine.wine_id
JOIN 
   wine_variety 
ON
   wine.wine_id = wine_variety.variety_id
WHERE 
   winery.region_id = region.region_id
AND 
   wine.winery_id = winery.winery_id";
if (!empty($wineName)) {
$query .= " AND w.wine_name = '{$wineName}'";
}

if (!empty($wineryName)) {
$query .= " AND winery.winery_name = '{$wineryName}'";
}

// If the user has specified a region, add the regionName 
// as an AND clause
if (isset($regionName) && $regionName != "All") {
$query .= " AND region.region_name = '{$regionName}'"; 
} 

// If the user has specified a variety, add the grapeVariety 
// as an AND clause
if (isset($grapeVariety) && $grapeVariety != "Riesling") {
$query .= " AND grape_variety.variety = '{$grapeVariety}'"; 
 }

如何正确编写MySQL别名？

4 个答案: