Table relationship:
question:
how to query the data shown in the figure using native sql statements?
expected data structure (the list item of the product appears as a nested object):
{
"category": [
{
"id": 1,
"name": "name1",
"product":[
{
"id":2,
"detail":""
},
{
"id":8,
"detail":""
}
]
}
]
}there are two ways,
category , and then traverse category to find product of each category , which will lead to Number1 query problems category , and then query all category.id to in , and match them in memory according to the relationship, as long as 2 times. recommend the second kind, Chestnut:
take out the category list you want
select * from category 1 id is put into in joint queries category_product and product to get product list
select category_id, product.id, product.detail from category_product where category_id in (...)
left join product
on category_product.product_id=product.id put the product obtained in 2 into the corresponding category.product array in 1 according to category_id .
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