android中query查询

最新推荐文章于 2022-12-30 09:58:23 发布

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最新推荐文章于 2022-12-30 09:58:23 发布

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分类专栏： query android 文章标签： android string query sms null scheme

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本文详细解析了SQL查询语句的使用方法，包括URI、projection、selection、selectionArgs和sortOrder参数的含义与应用，通过实例展示了如何进行复杂查询。

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uri	The URI, using the content:// scheme, for the content to retrieve.
projection	A list of which columns to return. Passing null will return all columns, which is inefficient.
selection	A filter declaring which rows to return, formatted as an SQL WHERE clause (excluding the WHERE itself). Passing null will return all rows for the given URI.
selectionArgs	You may include ?s in selection, which will be replaced by the values from selectionArgs, in the order that they appear in the selection. The values will be bound as Strings.
sortOrder	How to order the rows, formatted as an SQL ORDER BY clause (excluding the ORDER BY itself). Passing null will use the default sort order, which may be unordered.

URI 也就是要查询的表的 URI;

projection ：要查询的列

selection ：也就是一般的Sql语句跟在where后面的条件

selectionArgs：跟在where条件后面的查询条件的值

sortOrder: 不多说. 根据字段排序

Cursor 返回值我们可以理解为一个list集合

示例：表名 sms 有 id name gender age address number sessionId 等字段

假设要查询 sms表中 name,sessionId字段信息根据 gender 为 woman 且 number 值为 1022的查询条件来查询

uri= content://com.feng.jck /sms

String [] colums = {"name","sessionId"};

query(uri,colums,"gender = ? and number = ? ",new String[]{"woman","1022"},null);