Question

我目前正在教自己使用MySQL。问题是，自我教学并不总是那么容易，而且我常常陷入困境。通常情况下，我会试着让自己失望，但今天不是这样的一天。

我正在使用SQLFiddle（http://sqlfiddle.com/）对数据库运行查询，直到我找到一些更永久的软件解决方案。

我的问题出在我的查询中。

(SELECT customer.customername, the_account.balance, branch.branch_name    
   FROM customer, has_account, the_account, branch   
  WHERE customer.ssn = has_account.assn
    AND has_account.ano = the_account.accountno
    AND the_account.branchid = branch.branchid) AS a
JOIN
(SELECT customer.customername, loan.amount, branch.branch_name 
   FROM customer, has_loan, loan, branch
  WHERE customer.ssn = has_loan.lssn
    AND has_loan.lno = loan.loanno
    AND loan.branchid = branch.branchid) AS b
ON has_account.assn = has_loan.lssn;

现在，我确信语法错误对那些熟悉SQL的人来说是显而易见的，但我只是陷入了困境，似乎无法自拔。

我的理解是，我至少可以像这样尝试加入任意两个表。

有关我的数据库，查询等的完整概述，请转到http://sqlfiddle.com/#!2/1943b/85。

请，温柔。我知道这可能是一个新手的错误，但是你自己学习这些东西并不像你想象的那么容易。

UPDATE1：

所以在尝试了建议之后：

(SELECT has_account.assn as assn, customer.customername, the_account.balance, branch.branch_name    
   FROM customer, has_account, the_account, branch   
  WHERE customer.ssn = has_account.assn
    AND has_account.ano = the_account.accountno
    AND the_account.branchid = branch.branchid) AS a

JOIN

(SELECT has_loan.lssn as lssn, customer.customername, loan.amount, branch.branch_name 
   FROM customer, has_loan, loan, branch
  WHERE customer.ssn = has_loan.lssn
    AND has_loan.lno = loan.loanno
    AND loan.branchid = branch.branchid) AS b

ON b.lssn = a.assn;

看起来很好，并且对我来说世界上有意义，SQLFiddle抱怨道：

您的SQL语法有错误;检查手册对应于您的MySQL服务器版本，以便使用正确的语法 'AS a JOIN附近（SELECT has_loan.lssn as lssn，customer.customername， loan.amount，bra'在第5行:( SELECT has_account.assn as assn， customer.customername，the_account.balance，branch.branch_name FROM customer，has_account，the_account，branch WHERE customer.ssn = has_account.assn AND has_account.ano = the_account.accountno AND the_account.branchid = branch.branchid）作为一个加入（选择 has_loan.lssn as lssn，customer.customername，loan.amount， branch.branch_name FROM customer，has_loan，loan，branch WHERE customer.ssn = has_loan.lssn AND has_loan.lno = loan.loanno AND loan.branchid = branch.branchid）AS b ON b.lssn = a.assn

（以防万一有人想要完整的错误报告！）

Answer 1

select * from
(SELECT has_account.assn as assn, customer.customername, the_account.balance, branch.branch_name    
   FROM customer, has_account, the_account, branch   
  WHERE customer.ssn = has_account.assn
    AND has_account.ano = the_account.accountno
    AND the_account.branchid = branch.branchid) AS a
JOIN
(SELECT has_loan.lssn as lssn, customer.customername, loan.amount, branch.branch_name 
   FROM customer, has_loan, loan, branch
  WHERE customer.ssn = has_loan.lssn
    AND has_loan.lno = loan.loanno
    AND loan.branchid = branch.branchid) AS b
ON b.lssn = a.assn;

我个人不喜欢这样的连接，你可以用简单的方式尝试（我不确定连接条件是否正确，请检查）：

SELECT
  customer.customername,
  the_account.balance,
  branch.branch_name,
  loan.amount
FROM customer
JOIN has_account on has_account.assn = customer.ssn
JOIN the_account on the_account.accountno = has_account.ano
JOIN branch on branch.branchid = the_account.branchid
JOIN has_loan on has_loan.lssn = customer.ssn
JOIN loan on loan.loanno = has_loan.lno;

加入时MySQL语法错误

1 个答案: