MyBatis NULL Handling Guide

2 years ago
William Carter
1 minute

There are multiple ways to handle NULL values in MyBatis, such as using if, choose, and when tags.

  1. Handling NULL values using the if tag:
<select id="getUserById" parameterType="int" resultType="User">
    SELECT * FROM user WHERE id = #{id}
    <if test="name != null">
        AND name = #{name}
    </if>
</select>
  1. Handle NULL values using the choose and when tags.
<select id="getUserById" parameterType="int" resultType="User">
    SELECT * FROM user WHERE id = #{id}
    <choose>
        <when test="name != null">
            AND name = #{name}
        </when>
        <otherwise>
            AND name IS NULL
        </otherwise>
    </choose>
</select>
  1. Handle NULL values using ${} placeholders.
<select id="getUserByName" parameterType="String" resultType="User">
    SELECT * FROM user WHERE name = '${name}'
</select>

It is important to note that when using the ${} placeholder method, there is a risk of SQL injection. It is recommended to use #{name} to handle parameters.

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