SQLite合并两列的值

问题描述

我正在基于某种逻辑尝试从数据库中获取get数据，这是查询

String sql = "SELECT pr.number, pr.u_id from pro_cap pr " +
"LEFT OUTER JOIN pending p " +
"WHERE p.mobile_id = pr.u_id+pr.infant_no ";

待处理表中的 mobile_id 的value为4711

在 pro_cap 表中， u_id 的value是471，数字的值是1

我想从4711 = 4711的数据库中获取数据，但无法获取...

解决方案

要连接两个或更多列，请使用||运算符.

按如下所示更改查询:

String sql = "SELECT pr.number, pr.u_id from pro_cap pr " +
"LEFT OUTER JOIN pending p " +
"WHERE p.mobile_id = pr.u_id || pr.infant_no ";

I am trying get data from database based on some logic, here is the query

String sql = "SELECT pr.number, pr.u_id from pro_cap pr " +
"LEFT OUTER JOIN pending p " +
"WHERE p.mobile_id = pr.u_id+pr.infant_no ";

Where, value of mobile_id in pending table is 4711

And value of u_id is 471 and value of number is 1 in pro_cap table

I suppose to get data from database where 4711 = 4711, but unable to get...

解决方案

For concatenating two or more columns use || operator.

Change your query as below :

String sql = "SELECT pr.number, pr.u_id from pro_cap pr " +
"LEFT OUTER JOIN pending p " +
"WHERE p.mobile_id = pr.u_id || pr.infant_no ";

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