Question

sql 的insert插入语句有没有 判断如果存在就不插入 的限制语法

在这种形式下

<!--新增节点 -->
<insert id="addNode" parameterType="swust.seclab.domain.Node">
INSERT
INTO
Node
(Nod_nodecode,
Nod_parentcode,
Nod_nodetype,
Nod_nodeip,
Nod_nodename,
Nod_nodestate,
Nod_nodeport)
VALUES
(#{nodeCode,jdbcType=VARCHAR},
#{parentNodeCode,jdbcType=VARCHAR},
#{nodeType,jdbcType=VARCHAR},
#{nodeIp,jdbcType=VARCHAR},
#{nodeName,jdbcType=INTEGER},
#{nodeState,jdbcType=INTEGER},
#{nodePort,jdbcType=VARCHAR})
</insert>

Answer 1

INSERT
INTO
Node
(Nod_nodecode,
Nod_parentcode,
Nod_nodetype,
Nod_nodeip,
Nod_nodename,
Nod_nodestate,
Nod_nodeport)
select
各个变量
from dual
where not exists( select * from node
where 关键条件 )

Answer 2

if not exists(select * from Node where Nod_nodecode = '')

用exists可以判断啊

Answer 3

采用 insert into select 判断.