Question

我有SQL（postgresql）表达式，如下所示：

select * from table1 t1 left join table2 t2 on t1.id = t2.id where
t1.name = nameVariable and t2.field = fieldVariable;

如果nameVariable为null或为空而不执行“where”，是否可行？ t1.name = nameVariable“at all？

修改另外我需要确切地说我正在使用JPA和hibernate，所以查询看起来像这样：

@Query(value = " select * from table1 t1 left join table2 t2 on t1.id = t2.id where
    t1.name = :name and t2.field = :fieldName;", nativeQuery=true)
    public List<Test> getTest(@Param("name") String name, @Param("fieldName") String fieldName);

Answer 1

SELECT *
FROM table1 t1 
LEFT JOIN table2 t2 ON t1.id = t2.id
WHERE (t1.name = nameVariable OR nameVariable IS NULL)
AND (t2.field = fieldVariable OR t2.field IS NULL OR fieldVariable IS NULL)
   ;

如果变量为null或为空，则SQL排除where子句

1 个答案: