1.Oracle、MySQL插入时返回下一个主键的操作

Xml代码

Oracle：

SELECT SEQ_ROLE.NEXTVAL AS ID FROM DUAL

insert into ROLE(ID, NAME, CREATE, MODIFY) values (#{id}, #{name}, sysdate, sysdate)

注意：这边的keyProperty="id"中"id"指的是Java对象ROLE中的属性，而并非数据库中ROLE表的属性。

1.2.Oracle、MySQL插入时返回当前主键的操作

Oracle：

SELECT seq_LSP_ROLE.currval as ROLEID from DUAL

insert into ROLE(ID, NAME, CREATE, MODIFY) values (#{id}, #{name}, sysdate, sysdate)

MySQL:

insert into role (name, create_time, update_time) values (#{name,jdbcType=VARCHAR}, now(), now())

注意：role表的role_id字段是自动增长的，所以插入时不需要传入值；keyProperty="roleId"中"roleId"指的是Java对象Role中的属性，而并非数据库中role表的属性。

2.查询‘_’,'%' 这样的字符

java: roleName= roleName.replaceAll("_", "/_");

roleName= roleName.replaceAll("%", "/%");

resultType="java.lang.Integer">

SELECT COUNT(1) FROM LSP_ROLE_TAB T

AND T.ROLE_NAME LIKE CONCAT('%',CONCAT(#{roleName},'%')) ESCAPE '/'

AND T.DELETE_FLAG = 0

3.插入、修改时存储创建、修改时间为数据库时间

Oracle: insert into role(ID, NAME, CREATE, MODIFY) values (#{id}, #{name}, sysdate, sysdate)

MySQL: insert into role (name, create_time, update_time) values (#{name,jdbcType=VARCHAR}, now(), now())

4.关系运算符的处理及转义

主要处理的是小于/小于等于符号(”

...

包含在之间可避免

5.批量插入、修改、删除操作

insert into role_authority (role_id, authority_id) values      (${item.roleId}, ${item.authorityId})

DELETE FROM ld_user WHERE id IN        #{item}

6.模糊查询

AND t2.`name` LIKE "%"#{entName,jdbcType=VARCHAR}"%"

AND t3.`name` LIKE "%"#{prdName,jdbcType=VARCHAR}"%"

AND T.ROLE_NAME LIKE CONCAT('%',CONCAT(#{roleName},'%'))

6.分页

resultMap="BaseResultMap">

select

from (select ROWNUM as rn,

FROM LSP_MUTUALINFO_TAB t

and t.SERVER_NAME like CONCAT('%',CONCAT(#{serverName},'%')) escape '/'

and t.SERVER_ID = #{serverId,jdbcType=VARCHAR}

)

#{iPageIndex} ]]>

1、将根据name相同 ID不同来的方式来判断(id必须唯一)

delete from test a where exists (select null from test b where b.name=a.name and b.id>a.id);

2、用rowid 来代替其中的id，比上面的方法更适用，没有字段唯一限制

delete from test a where exists (select null from test b where b.name=a.name and b.rowid>a.rowid);

3、  通过分析函数根据name 分组生成序号，然后删除序号大于1 的数据

这里的ROW_NUMBER() OVER (partition by name order by name) 是先把name列升序，再为降序以后的没条name记录返回一个序号，

delete from test     where rowid in (select rowid                       from (select rowid as rid,                                    row_number() over(partition by name order by id) as seq                               from test)                      where seq > 1);