如何在 Android 应用程序中执行 SQLite 查询？
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How to perform an SQLite query within an Android application?
提问by Dennie
I am trying to use this query upon my Android database, but it does not return any data. Am I missing something?
我正在尝试在我的 Android 数据库上使用此查询，但它不返回任何数据。我错过了什么吗？
SQLiteDatabase db = mDbHelper.getReadableDatabase();
String select = "Select _id, title, title_raw from search Where(title_raw like " + "'%Smith%'" +
")";
Cursor cursor = db.query(TABLE_NAME, FROM,
select, null, null, null, null);
startManagingCursor(cursor);
return cursor;
回答by Prashast
This will return you the required cursor
这将返回您所需的游标
Cursor cursor = db.query(TABLE_NAME, new String[] {"_id", "title", "title_raw"},
"title_raw like " + "'%Smith%'", null, null, null, null);
回答by xiojason
Alternatively, db.rawQuery(sql, selectionArgs) exists.
或者， db.rawQuery(sql, selectionArgs) 存在。
Cursor c = db.rawQuery(select, null);
回答by Gautam Mandsorwale
This will also work if the pattern you want to match is a variable.
如果您要匹配的模式是变量，这也将起作用。
dbh = new DbHelper(this);
SQLiteDatabase db = dbh.getWritableDatabase();
Cursor c = db.query("TableName", new String[]{"ColumnName"}
, "ColumnName LIKE ?" ,new String[]{_data+"%"}, null, null, null);
while(c.moveToNext())
{
// your calculation goes here
}
回答by Suragch
I came here for a reminder of how to set up the query but the existing examples were hard to follow. Here is an example with more explanation.
我来这里是为了提醒如何设置查询，但现有示例很难遵循。这是一个带有更多解释的示例。
SQLiteDatabase db = helper.getReadableDatabase();
String table = "table2";
String[] columns = {"column1", "column3"};
String selection = "column3 =?";
String[] selectionArgs = {"apple"};
String groupBy = null;
String having = null;
String orderBy = "column3 DESC";
String limit = "10";
Cursor cursor = db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy, limit);
Parameters
参数
table: the name of the table you want to querycolumns: the column names that you want returned. Don't return data that you don't need.selection: the row data that you want returned from the columns (This is the WHERE clause.)selectionArgs: This is substituted for the?in theselectionString above.groupByandhaving: This groups duplicate data in a column with data having certain conditions. Any unneeded parameters can be set to null.orderBy: sort the datalimit: limit the number of results to return
table: 要查询的表名columns: 要返回的列名。不要返回不需要的数据。selection：您希望从列返回的行数据（这是 WHERE 子句。）selectionArgs：这是代替?在selection上面的字符串。groupBy和having：这将具有特定条件的数据分组到列中的重复数据。任何不需要的参数都可以设置为空。orderBy: 对数据进行排序limit: 限制返回的结果数
回答by styling
Try this, this works for my code name is a String:
试试这个，这适用于我的代号是一个字符串：
cursor = rdb.query(true, TABLE_PROFILE, new String[] { ID,
REMOTEID, FIRSTNAME, LASTNAME, EMAIL, GENDER, AGE, DOB,
ROLEID, NATIONALID, URL, IMAGEURL },
LASTNAME + " like ?", new String[]{ name+"%" }, null, null, null, null);
