# MyBatis3

**Repository Path**: zhtt/mybatits3

## Basic Information

- **Project Name**: MyBatis3
- **Description**: No description available
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2017-04-22
- **Last Updated**: 2020-12-19

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# MyBatits3

## 建表语句
```  sql
CREATE DATABASE test3 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
CREATE TABLE IF NOT EXISTS zdshbzryexcel(
   id INT UNSIGNED AUTO_INCREMENT,
   xm VARCHAR(100) ,
   xb VARCHAR(40) ,
   jtgx VARCHAR(40),
   PRIMARY KEY ( id )
)ENGINE=InnoDB DEFAULT CHARSET=utf8;


create database test4 DEFAULT CHARACTER SET gbk COLLATE gbk_chinese_ci;
CREATE TABLE IF NOT EXISTS zdshbzryexcel(
   id INT UNSIGNED AUTO_INCREMENT,
   xm VARCHAR(100) ,
   xb VARCHAR(40) ,
   jtgx VARCHAR(40),
   PRIMARY KEY ( id )
)ENGINE=InnoDB DEFAULT CHARSET=gbk;

```
## mysql乱码解决方法
* 1、停止mysql服务
services.msc

* 2、打开配置文件
C:\Program Files\MySQL\MySQL Server 5.0\my.ini

* 3、修改配置文件
在[client]、[mysql]、[mysqld]
无则增加、有则修改
default-character-set=utf8

## mybatis sql相关
### 批量执行SQL
``` sql
<delete id="delete">
    begin
        delete from t_user where id=#{id};
        delete from r_user_role where user_id=#{id};
    end;
</delete>
```
### 指定全局表名
``` sql
<sql id="user">table_space_name.t_user</sql>
<select id="query" parameterType="zhtt.entity.User">
    select * from <include refid="user"/>
</select>
```
### 批量更新
 1. java代码如下：
 ```
public void addEmps(@Param("emps")List<Employee> emps);
```
 2. sql语句如下：
```
<insert id="addEmps">
        INSERT INTO tb1_emplyee(last_name,email,gender,d_id)
        VALUES
        <foreach collection="emps" item="emp" separator=",">
            (#{emp.lastName},#{emp.email},#{emp.gender},#{emp.dept.id})
        </foreach>
</insert>
```
### 逻辑比较
  First Header  | Second Header| Second Header
  ------------- | -------------| -------------
  &  | `&amp;`|
  '  | `&apos;`
  "  | `&quot;`
  <  | `&lt;`|`<![CDATA[ < ]]>`
  <=  | `&lt;=`|`<![CDATA[ <= ]]>`
  `>`  | `&gt;`|`<![CDATA[ > ]]>`
  `>=`  | `&gt;=`|`<![CDATA[ >= ]]>`

## 查询时的特殊符号
``` java
  public static String decode(String str, String defaultValue) {
        if (str == null) {
            return defaultValue;
        }
        try {
            return URLDecoder.decode(str, "UTF-8");
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return defaultValue;
        }
    }

import org.springframework.util.StringUtils;

public class SpecialCharacherUtils {
	public static String toMyString(String oldString) {
		String symbol = "";
		if(oldString.contains("%")){
			symbol = "%";
		}else if(oldString.contains("_")){
			symbol = "_";
		}else if(oldString.contains("[")){
			symbol = "[";
		}else if(oldString.contains("]")){
			symbol = "]";
		}else{
			return oldString;
		}
		if (!StringUtils.isEmpty(oldString)) {
			int length = oldString.length();
			String repString = "*";
			int flag = oldString.indexOf(symbol);
			String newString1 = oldString.substring(0, flag);
			String newString2 = oldString.substring(flag, length);
			String newString = newString1 + repString + newString2;
			return newString;
		} else {
			return oldString;
		}
	}
}

 '%' || #{_like_name} || '%' ESCAPE '*'
```
* 多条件逻辑判断
``` sql 
<if test='id != null and id > 28'></if>
```