Mybatis 动态sql语句（if标签和where标签）

古城微笑少年丶 2023-10-03 13:58 42阅读 0赞

功能：根据性别和名字查询用户

查询sql语句：

SELECT id, username, birthday, sex, address FROM \`user\` WHERE sex = 1 AND username LIKE '%张%'  
mybatis动态sql：

Mapper.xml文件配置sql如下：

<select id="queryUserByWhere" parameterType="user" resultType="user">  
SELECT id, username, birthday, sex, address FROM \`user\`  
WHERE sex = \#\{sex\} AND username LIKE  
'%$\{username\}%'  
</select>  
改进1：

<select id="queryUserByWhere" parameterType="user" resultType="user">  
SELECT id, username, birthday, sex, address FROM \`user\`  
WHERE 1=1  
<if test="sex != null and sex != ''">  
AND sex = \#\{sex\}  
</if>  
<if test="username != null and username != ''">  
AND username LIKE  
'%$\{username\}%'  
</if>  
</select>  
改进2：

<select id="queryUserByWhere" parameterType="user" resultType="user">  
SELECT id, username, birthday, sex, address FROM \`user\`  
  
<where>  
<if test="sex != null">  
AND sex = \#\{sex\}  
</if>  
<if test="username != null and username != ''">  
AND username LIKE  
'%$\{username\}%'  
</if>  
</where>  
</select>  
  
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原文链接：https://blog.csdn.net/guanmao4322/article/details/99696541