错误写法：
<if test="codeFlag == '1'">
AND SUBSTR(a.code,-4) = '0000'
</if>
<if test="codeFlag == '2'">
AND SUBSTR(a.code,-4) != '0000' AND SUBSTR(a.code,-2) = '00'
</if>
正确写法：
//codeFlag为String型或者整型；
//codeFlag为String型,字母字符串时，才加单引号
<if test="codeFlag == 1">
AND SUBSTR(a.code,-4) = '0000'
</if>
<if test="codeFlag == 2">
AND SUBSTR(a.code,-4) != '0000' AND SUBSTR(a.code,-2) = '00'
</if>
