trim元素的主要功能是可以在自己包含的内容前加上某些前缀，也可以在其后加上某些后缀，与之对应的属性是prefix和suffix；可以把包含内容的首部某些内容覆盖，即忽略，也可以把尾部的某些内容覆盖，对应的属性是prefixOverrides和suffixOverrides；
<insert id="operatorLog" parameterType="com.oa.model.wxlog.WxLog">
INSERT INTO sdb_oa_operator_log
<trim prefix="(" suffix=")" suffixOverrides="," >
<if test="open_id!='' and open_id != null">
open_id,
</if>
<if test="operatortime!='' and operatortime != null">
operatortime,
</if>
<if test="operatortype!='' and operatortype != null">
operatortype,
</if>
<if test="operatorcont!='' and operatorcont != null">
operatorcont,
</if>
<if test="ip!='' and ip != null">
ip,
</if>
</trim>
<trim prefix="values(" suffix=")" suffixOverrides="," >
<if test="open_id!='' and open_id != null">
#{open_id},
</if>
<if test="operatortime!='' and operatortime != null">
#{operatortime},
</if>
<if test="operatortype!='' and operatortype != null">
#{operatortype},
</if>
<if test="operatorcont!='' and operatorcont != null">
#{operatorcont},
</if>
<if test="ip!='' and ip != null">
#{ip},
</if>
</trim>
</insert>
Mybatis 配置文件 useGeneratedKeys 参数只针对 insert 语句生效，默认为 false。
当设置为 true 时，表示如果插入的表以自增列为主键，则允许 JDBC 支持自动生成主键，并可将自动生成的主键返回。
<insert id="saveMain" parameterType="java.util.HashMap" keyProperty="id" useGeneratedKeys="true">
insert into <include refid="tableName"></include>(
<include refid="Field"></include>
) values (
<include refid="FieldValue"></include>
)
</insert>
--------------Mybatis 拼接like ---
and date_format(company.create_time,'%Y-%m-%d %H:%i:%s') LIKE CONCAT('%', '${params.create_time}', '%')
----------------mybatis 判断参数要加.toString()---
<if test="params.selectTime =='2'.toString() ">