mybatis动态sql

1：简单的if

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<select id="dynamicIfTest" parameterType="Model" resultType="Model">  
	select * from t_blog where 11 = 1  
	<if test="title != null">  
		and title = #{title}  
	</if>  
	<if test="content != null">  
		and content = #{content}  
	</if>  
	<if test="owner != null">  
		and owner = #{owner}  
	</if>  
</select>

简述，这里的title != <if test="title != null"> 也支持 title != <if test="title != ‘ ‘ ">?

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2：choose语句

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<select id="dynamicChooseTest" parameterType="Model" resultType="Model">  
	select * from t_blog where 11 = 1   
	<choose>  
		<when test="title != null">  
			and title = #{title}  
		</when>  
		<when test="content != null">  
			and content = #{content}  
		</when>  
		<otherwise>  
			and owner = "owner1"  
		</otherwise>  
	</choose>  
</select>  

?简述，当when中有条件满足的时候，就会跳出choose（和if else if else 差不多）如果两个when都不满足，则<otherwise>代码块就会执行。

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3：where 标签

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<select id="dynamicWhereTest" parameterType="Blog" resultType="Blog">  
    select * from t_blog   
    <where>  
        <if test="title != null">  
            title = #{title}  
        </if>  
        <if test="content != null">  
            and content = #{content}  
        </if>  
        <if test="owner != null">  
            and owner = #{owner}  
        </if>  
    </where>  
</select> 

?简述，这个<where>标签的好处就是自动只能的给你添加 and 和 or 关键字，比如tile == null 而 content !=null 就会输出 select * from t_blog? where content = #{content} 自动去掉 and 很只能吧！

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这些基本就够用了！

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mybatis动态sql

原文：http://zliguo.iteye.com/blog/2262911