Cause: java.sql.SQLIntegrityConstraintViolationException: Column ‘xxx‘ cannot be null

1、报错信息

2、定位错误的范围
### SQL: insert into business
(businessId,password,salt,businessName,businessAddress,businessExplain,starPrice,deliveryPrice)
values (?,?,?,?,?,?,?,?)
3、从上述报错内容已知错误存在于SQL的insert into操作里，然后跳转到BuseineeMapper.xml里

4、定位到BusinessMapper.xml里的id为add的部分
<insert id="add" parameterType="Business" useGeneratedKeys="true"> <!--
使用数据库的自增列管理businessId值，并保存到Business类的businessId属性中 --> <selectKey
keyColumn="businessId" keyProperty="businessId" resultType="int"> select
last_insert_id() as businessId </selectKey> insert into business
(businessId,password,salt,businessName,businessAddress,businessExplain,starPrice,deliveryPrice)
values
(#{businessId},#{password},#{salt},#{businessName},#{businessAddress},#{businessExplain},#{starPrice},#{deliveryPrice})
</insert>
5、发现sql语句和xml标签没写错，排除问题存在于BusinessMapper.xml

6、最后发现businessId是必填字段而且是主键，但没有给businessId勾选自动递增，所以插入数据时因为businessId没值且不自增而导致异常

7、勾选上自动递增并保存，运行成功

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