springboot + mybatis multi-database support

1. placed application.yml

mybatis:
  mapper-locations: classpath:/mybatis/mapping/*.xml
  configuration:
    map-underscore-to-camel-case: true #开启驼峰命名
 database-id: ${database.type}
 type-aliases-package: com.mtwl.entity

Note that the configuration of database-id 
2. DatabaseIdProvider disposed in the springboot

@Bean
public DatabaseIdProvider getDatabaseIdProvider(){
    DatabaseIdProvider databaseIdProvider = new VendorDatabaseIdProvider();
    Properties properties = new Properties();
    properties.setProperty("Oracle","oracle");
 properties.setProperty("MySQL","mysql");
 properties.setProperty("DB2","db2");
 properties.setProperty("Derby","derby");
 properties.setProperty("H2","h2");
 properties.setProperty("HSQL","hsql");
 properties.setProperty("Informix","informix");
 properties.setProperty("In the Microsoft SQL Server", "sqlserver"); 
properties.setProperty ( "PostgreSQL", "PostgreSQL"); 
properties.setProperty ( "Sybase", "Sybase"); 
properties.setProperty ( "Hana", "hana"); 
databaseIdProvider.setProperties (Properties); 
 return databaseIdProvider; 
} 
Note: the correct version of the database 
3. in mapper.xml in 
method 1

<select id="selectTop" resultType="java.util.Map" parameterType="java.lang.Integer" databaseId="sqlserver">
 select top(#{value})*
 from kcjs
 </select>

<select id="selectTop" resultType="java.util.Map" parameterType="java.lang.Integer" databaseId="mysql">
 select *
 from kcjs limit 0,#{value}
</select>


方法2

<select id="selectTop" resultType="java.util.Map" parameterType="java.lang.Integer">
 select
 <if test="_databaseId==sqlserver">
 top(#{value})*
 from kcjs
 </if>
 <if test="_databaseId==mysql">
 *
 from kcjs limit 0,#{value}
 </if>

</select>