How to write MySQL aliases properly? - php

Question

For all those that care, I found that I needed to re read the basics on querying. Once sorted, I realised I had a fair few errors throughout my code.
I've got a query I'm trying to build and I'm throwing up error after error regarding to ambiguity. Would anyone kindly show me how to execute MySQL aliases properly?
This is my code so far. It worked fine until I put the join in there. I suspect it's because I'm referencing 'wine' more than once in the same query, but that may be one of many problems.
$query =
"SELECT
wine_id,
wine_name,
winery_name,
region_name,
year,
variety
FROM
wine AS w,
winery,
region,
grape_variety
JOIN
wine
ON
grape_variety.variety_id = wine.wine_id
JOIN
wine_variety
ON
wine.wine_id = wine_variety.variety_id
WHERE
winery.region_id = region.region_id
AND
wine.winery_id = winery.winery_id";
if (!empty($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

Try to do it this way:
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

Your query must be like:
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
Note: if you give table structure then it would be more clear, at first I assume whatever column you retrieve is from main table and
if all tables in query have same column name then use table_alias_name.column_name.

Answer 3

try this
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

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