java study notes --mybatis framework often encounter a problem link collection

Before learning to do java development, did not write blog. Solution found on the Internet, the link saved.

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1 mybatis jdbcType common data types
     https://www.cnblogs.com/lixuwu/p/5916585.html
    
2 0 Mybatis determined null question
    https://blog.csdn.net/weixin_37645838/article/details/83088932
    
. 3 the ASCII code
    http://www.asciima.com/