MyBatis if 子句

Question

我尝试在 MyBatis 中遵循 if 子句并得到以下异常请帮助我确定这里的问题..

public class Student{

private Integer studId;
private String name;
private String email;
private Date dob;
}

映射

<select id="searchStudent" parameterType="hashmap" resultMap="StudentResult">
    <![CDATA[
    SELECT * FROM STUDENTS
    WHERE 1 = 1 

    <if test="studId != null">
    AND STUD_ID= #{studId}
    </if>

    <if test="name != null">
    AND NAME like #{name}
    </if>

    ]]>
</select>

我得到的异常:

Exception in thread "main" org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL   syntax; check the manual that corresponds to your MySQL server version for the right syntax   to use near 'test="studId != null">
    AND STUD_ID= 1
    </if>

    <if test="name != null">
    ' at line 4
### The error may exist in StudentMapper.xml
### The error may involve com.maventest.mytest.StudentMapper.searchStudent-Inline
### The error occurred while setting parameters
### SQL: SELECT * FROM STUDENTS   WHERE 1 = 1       <if test="studId != null">   AND STUD_ID= ?   </if>      <if test="name != null">   AND NAME like ?   </if>
### Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'test="studId != null">
    AND STUD_ID= 1
    </if>

    <if test="name != null">
    ' at line 4
at    org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:23)

Answer 1

删除 <![CDATA[和 ]]>因为这会转义所有查询并且 mybatis 根本不会处理它所以 if作为数据库查询的一部分逐字传递。

<select id="searchStudent" parameterType="hashmap" resultMap="StudentResult">
  SELECT * FROM STUDENTS
  WHERE 1 = 1 

  <if test="studId != null">
    AND STUD_ID= #{studId}
  </if>

  <if test="name != null">
    AND NAME like #{name}
  </if>

</select>