sql標籤:抽取可重用的sql片段,方便後面引用;
1. sql抽取:經常將要查詢的列名,或者插入用的例名抽取出來方便引用;
2. include標籤用來引用已經抽取出來的sql;
3. include還可以自定義一些 property, sql標籤內部就可以使自定義的屬性;
include–property:取值的正確方法:${prop}
#{不能使用這種方式}
<insert id="addEmps">
insert into(
<include refid="insertColumn">
<property name="testColomn" value="abc"/>
</include>
)
valuse(
<foreach collection="emps" item="emp",separator=",">
#{emp.lastName},#{emp.email,},#{emp.gender},#{emp.dept.id}
</foreach>
)
</insert>
<sql id="insertColumn">
<if test="_databaseId=='oracle'">
employee_id,last_name,email,${testColomn}
</if>
<if test="_databaseId=='mysql'">
last_name,email,gender,d_id
</if>
</sql>