子查询返回多行MySQL(Subquery returns more than 1 row MySQL)

 嘿所以有这两个表名称和代码，我试图创建一个包含所有名称的表，并将每个现有代码与名称相匹配。 某些名称没有代码，因此它们应显示为NULL。 无论如何这是我的代码： 
 
SELECT company.name,

(SELECT companyclassification.code
FROM insure_prod.companyclassification
WHERE  company.OIQ_ID = companyclassification.ussicClassification_StdCompany)
AS USSIC_Code

FROM insure_prod.company
 
 当我尝试运行它时，它显示错误代码：1242子查询返回超过1行 
 
 提前致谢 

Hey so there are these two tables Name and Code and I am trying to make a table with all the Names and match each existing code to the names. Some Names do not have codes so it should display as NULL for those ones. Anyways this is my code:
 
SELECT company.name,

(SELECT companyclassification.code
FROM insure_prod.companyclassification
WHERE  company.OIQ_ID = companyclassification.ussicClassification_StdCompany)
AS USSIC_Code

FROM insure_prod.company
 
When I try to run this it displays Error Code: 1242 Subquery returns more than 1 row
 
Thanks in advance

原文：https://stackoverflow.com/questions/17477398