官方参考文档:SQLite Query Language: Core Functions http://www.sqlite.org/lang_corefunc.html 测试SQL语句: ,) AS substr_0_20, substr(,) AS substr_0_19, substr(,) AS substr_1_19, substr() AS substr_19 WINDOW上的Navicat.Mac上的MesaSQLite.Android上SQLite上测试语句结果:substr_0