1.按長(zhǎng)度查詢匹配：length
select?length(字段名) from? 表名;
select 字段名? from? 表名 where length(字段名)>20;
2.字符轉(zhuǎn)int類型查詢匹配
select? cast(字段名 as SIGNED INTEGER) from?表名;
select 字段名? from? 表名 where?cast(字段名 as SIGNED INTEGER)>20;
3.插入數(shù)據(jù)忽略失敗的數(shù)據(jù)行
insert ignore into 表名
4.若數(shù)據(jù)表中存在相同主鍵記錄泛烙，則更新
insert? into 表名(update_date)?VALUES (變量值)?ON DUPLICATE KEY UPDATE?update_date=VALUES(update_date)
5.foreach使用
select 字段 from 表名 where 字段? in
<foreach collection="list" item="item" index="index" open="(" close=")" separator=",">
????????#{item}
? </foreach>
insert? into 表名(字段)? values
<foreach collection="list" item="item" index="index" separator="," >
? ? ? ( #{item.字段變量})
? </foreach>
<foreach collection="list" item="item" index="index" open="" close="" separator=";">
? ??????insert? into 表名(字段)? values?? ( #{item.字段變量})
</foreach>
