Android如何用适当的投影编写查询? [英] Android how to write the query with a proper projection?

问题描述

我有一个名为 TermTable 的 sqlite 表，其中包含 id、selected、term 和 type 列:

I have a sqlite table called TermTable with id, selected, term and type columns:

static final String TermTable = "Terms";
static final String ID = "id";
static final String Selected = "selected";
static final String Term = "term";
static final String Type = "type";

我创建的表如下:

private static final String TERM_TABLE_CREATE = "Create table " + TermTable +
    "(" + ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
    Selected + " VARCHAR(5) ," +
    Term + " VARCHAR(20) ," +
    Type + " VARCHAR(10))";

selected"列获取字符串true"或false".

现在我想查询并获取将字符串作为 term 获取的游标如果它的 selected 列为真，则返回 id 和 type 列:

The column "selected" gets the strings "true" or "false".

Now I want to query and get the cursor which gets a string as a term and if its selected column is true, returns the columns id and type:

public Cursor getFavoriteValues(String term)
{
    String from[] = { "id", "type" };
    String where = ???
    String whereArgs[] = ???
    Cursor cursor = db.query(WordsDB.TermTable, from, where, whereArgs, null, null, null, null);
    return cursor;
}

这个查询属性是如何定义的?

How are this query attributes defined?

推荐答案

public Cursor getTermValues(String term)
{
    String from[] = { "id", "Type" };
    String where = WordsDB.Selected + "=? AND " + WordsDB.Term + "=?";
    String whereArgs[] = new String[]{ "true", term };
    return db.query(WordsDB.TermTable, from, where, whereArgs, null, null, null, null);
}

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