Monthly Archives: April 2019

DQL常用操作及常见问题

DQL: Database Query Language

1、查询某字段去重复

  • select distinct xxxx from xxxx

2、合并字段查询函数concat( )、concat_ws( )

  • select concat(user_name, password) from user;
  • select concat(user_name, password) as user_name_email from user;
  • select concat_ws(‘->’, user_name, password) from user; // 查询结果用’->’分隔符隔开
    [……]

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