springboot+springmvc+mybatis 使用注解对数据库的增、改和查操作

最近在做java后台所遇到的问题和总结，本文针对的是springboot+springmvc+mybatis 环境下的，所用的数据库是oracle。

一、普通查询，参数为map，注解和方法的例子如下：

@Select("select ID,BIDas bid,CUSTOMER_BUS_ID as CBID," +
"MD5,OWNERID,STATUS,FIELD_NAME as fieldName,FIELD_INDEX as fieldIndex," +
"FIELD_CONTENT as fieldContent, CREATE_TIME as createTime,UPDATE_TIME " +
"as updateTime,SPARE1,SPARE2,SPARE3 from 表名 t  where t.ownerada = #{ownerID} and t.business_id = #{bId}")

public AEntity findCustomerFieldByMap(Map map);

注意：

1.有数据库的字段名是有下划线的，而实体类的属性是按照java命名规则来命名的，这就导致了数据库的字段名和实体的属性名不一致，所以要使用as别名才可以查出结果，否则就会出现数据库有数据，但是你查询的时候是查不出来的；例如：FIELD_NAME as fieldName    。

2.由于查询的参数是map，所以查询条件所传入的值是map的key，例如：t.ownerada = #{ownerID}

3.因为数据库的字段名和实体的属性名不一致，所以不能使用select * 查询。

二、in查询，参数为map，注解和方法的例子如下：

@Select("select ID,BIDas businessId,CBID as customerBusId," +
"MD5,OWNERID,STATUS,FIELD_NAME as fieldName,FIELD_INDEX as fieldIndex," +
"FIELD_CONTENT as fieldContent, CREATE_TIME as createTime,UPDATE_TIME " +
"as updateTime,SPARE1,SPARE2,SPARE3 from mstb_crm_customer_field t " +
"where t.CBID in ${customerBusId}")

public List findCustomerFieldListByMap( Map map);

注意：在用in查询的时候，参数要使用$，而不是#。其他要注意的和普通查询一样。

三、插入数据，参数为对象，注解和方法的例子如下：

@Insert("INSERT INTO mstb_crm_customer_field(ID,BID,CBID," +
"MD5,OWNERADA,STATUS,FIELD_NAME,FIELD_INDEX,FIELD_CONTENT," +
"CREATE_TIME,UPDATE_TIME,SPARE1,SPARE2,SPARE3)" +
"VALUES(MSTB_CRM_CUSTOMER_FIELD_SEQ.nextval," +
"#{businessId,jdbcType=VARCHAR}," +
"#{customerBusId,jdbcType=VARCHAR}," +
"#{md5,jdbcType=VARCHAR}," +
"#{ownerada,jdbcType=VARCHAR}," +
"#{status,jdbcType=INTEGER}," +
"#{fieldName,jdbcType=VARCHAR}," +
"#{fieldIndex,jdbcType=INTEGER}," +
"#{fieldContent,jdbcType=VARCHAR}," +
"#{createTime,jdbcType=TIMESTAMP}," +
"#{updateTime,jdbcType=TIMESTAMP}," +
"#{spare1,jdbcType=VARCHAR}," +
"#{spare2,jdbcType=VARCHAR}," +
"#{spare3,jdbcType=VARCHAR})")
public void insert(MstbCrmCustomerField customerField) ;

注意：在插入的时候有些值允许为空的，则要加上jdbcType，这样在插入的时候才不会报错；不允许为空的可以不加jdbcType，但是防止出错和以后数据维护，建议所有的参数都加上jdbcType。

四、修改数据，参数为对象，注解和方法的例子如下：

@Update("UPDATE mstb_crm_customer_field SET BID=#{businessId,jdbcType=VARCHAR}," +
"CBID=#{customerBusId,jdbcType=VARCHAR}," +
"MD5=#{md5,jdbcType=VARCHAR}," +
"OWNERADA=#{ownerada,jdbcType=VARCHAR}," +
"STATUS=#{status,jdbcType=INTEGER}," +
"TITLE=#{fieldName,jdbcType=VARCHAR}," +
"WORK_DATE=#{fieldIndex,jdbcType=INTEGER}," +
"CONTENT=#{fieldContent,jdbcType=VARCHAR}," +
"CREATE_TIME=#{createTime,jdbcType=TIMESTAMP}," +
"UPDATE_TIME=#{updateTime,jdbcType=TIMESTAMP}," +
"SPARE1=#{spare1,jdbcType=VARCHAR}," +
"SPARE2=#{spare2,jdbcType=VARCHAR}," +
"SPARE3=#{spare3,jdbcType=VARCHAR}" +
" WHERE ID=#{id,jdbcType=INTEGER}")  
public void update(MstbCrmCustomerField customerField) ;

注意：修改要注意的和新增的一样。