Finding a SQL statement that is not difficult

dark_paladin201

2 tables, 1 is the parts list bj (one field represents the part code and one field is the flag tag), and 1 is the price list jg (there is also a part code field and a price field)

Now find the price of all parts whose flag is true.

select bj.id, jg.jg from bj, jg where bj.flag = 1

The problem is that in the price list, the prices of some parts do not exist. According to the above query, only the parts that exist in both tables are available, but I cannot get a list of all parts with flag = 1.

The requirement is to get a list of all parts with flag = 1. If any part does not exist in the price list, it will automatically take 0.

dark_paladin201

select bj.id,jg.jg from bj,jg where bj.flag=1 and bj.id=jg.id

身材正

select bj.id
       ISNULL(jg.jg,0)
left join jg on bj.id=jg.id
where bj.flag=1

siyonggang

select bj.id,jg.jg from bj left outer join jg on bj.id=jg.id where bj.flag=1

bj.id=jg. Part code field after on (if id is part id column)

fenghui1231

Positive solution on the first floor

dark_paladin201

I did it myself, and it was very complicated. I used union, and set the price of the parts already in the price list + the price of the parts that did not exist in the price list to 0.

jcsexy

SELECT bj.id,IsNull(jg.jg,0)
FROM bj,jg
WHERE bj.id=jg.id(+) and bj.flag=1