Java DB，如何计算 Union 中的行数 select

Question

我想知道如何计算这个 select Java 数据库中联合的行数

Select R.ID , R.CAPACITE from ASSISTE  A
join REPRESENTATION R on R.ID = A.IDREPRESENTATION
where R.ID = 7
union all
SELECT R.id ,R.CAPACITE FROM BILLET B 
    join REPRESENTATION R on R.ID = B.IDREPRESENTATION
    where R.ID = 7

我试过

Select count(*) from (Select R.ID , R.CAPACITE from ASSISTE  A
    join REPRESENTATION R on R.ID = A.IDREPRESENTATION
    where R.ID = 7
union all
SELECT R.id ,R.CAPACITE FROM BILLET B 
    join REPRESENTATION R on R.ID = B.IDREPRESENTATION
    where R.ID = 7  )

但是我收到了这个错误！

Error code 30000, SQL state 42X01: Erreur de syntaxe : Encountered "<EOF>" at line 7, column 21.
Line 2, column 1

请帮忙 :D

Answer 1

我想你忘了在最后添加别名。尝试这样的事情：

Select count(*) from (
Select R.ID , R.CAPACITE from ASSISTE  A
    join REPRESENTATION R on R.ID = A.IDREPRESENTATION
    where R.ID = 7
union all
SELECT R.id ,R.CAPACITE FROM BILLET B 
    join REPRESENTATION R on R.ID = B.IDREPRESENTATION
    where R.ID = 7  
) A

Java DB，如何计算 Union 中的行数 select

Java DB, How to count row in Union select

union

count

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