本文介绍了Android的SQLite的返回-1，getColumnIndex列时存在明显的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
当我在表中插入临时值到所有的列，它似乎工作。请参阅下面的方法和下面登录。但是，当我测试，如果列存在，我在下面的测试方法，该列存在返回false !!
的code中的第一个片段展示了从那里临时值和方法，如果某列存在的测试被调用。下面的代码片段包括日志，如何创建表，并调用的方法。谢谢！
ContentValues值= setContVal_All_Columns（myTable的）;
//创建一行
长insertId = database.insert（myTable的，空，价值观）;
的System.out.println（列日存在=+将String.valueOf（doesColumnExist（myTable的，日）））;
setContVal_All_Columns方法：
//设置通用内容值初始化行=不包括ID列
私人ContentValues setContVal_All_Columns（字符串myTable的）{
ContentValues contentValues =新ContentValues（）;
光标光标= database.query（myTable的，NULL，NULL，NULL，NULL，NULL，NULL）;
的String [] columnNames = cursor.getColumnNames（）;
cursor.moveToFirst（）;
对于（字符串名称：columnNames）{
如果（！name.equals（IdColumn））{//排除Id列
INT指数= cursor.getColumnIndex（名称）;
的System.out.println（列名=+姓名+指数=+将String.valueOf（指数））;
的System.out.println（类型=+将String.valueOf（cursor.getType（索引）））; //出现崩溃的的getType
如果（cursor.getType（指数）== 3）{//串
的System.out.println（栏中的字符串）;
contentValues.put（姓名，）;
}否则，如果（cursor.getType（指数）== 1）{//整数
contentValues.put（姓名，0）;
}
}
}
返回contentValues;
}
方法进行测试如果列同时存在：总是返回-1日期列...
私人布尔doesColumnExist（字符串myTable的，字符串根据MyColumn）{
布尔doesExist = TRUE;
光标光标= database.rawQuery（杂table_info（+为myTable +），NULL）;
cursor.moveToFirst（）;
int值= cursor.getColumnIndex（根据MyColumn）;
如果（价值== -1）
{
doesExist = FALSE;
}
返回doesExist;
}
日志信息：
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列名=日期索引= 1
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders I / System.out的：类型= 0
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列名=名称指数= 2
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders I / System.out的：类型= 3
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列是字符串
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列名=海拔指数= 3
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders I / System.out的：类型= 0
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列名= is_used指数= 4
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders I / System.out的：类型= 0
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列名=预警指数= 5
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders I / System.out的：类型= 0
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列名=动作指数= 6
02-16 19：58：42.296 9711-9711 / com.mycompany.dudesmyreminders I / System.out的：类型= 0
02-16 19：58：42.316 9711-9711 / com.mycompany.dudesmyreminders我/的System.out：列日存在=假
表创建方法：
//数据库创建SQL语句
私有静态最后弦乐SQL_CREATE_SPECIAL_DAYS =
CREATE TABLE+ dbFields.TABLE_NAME_SPECIAL_DAYS +（+
dbFields.COLUMN_SPECIAL_DAYS_ID + INTEGER_PRIMARY_KEY + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_DATE + TEXT_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_NAME + TEXT_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_ALTITUDE + INTEGER_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_USED + INTEGER_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_WARNING + INTEGER_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_ACTION + INTEGER_TYPE +
//任何其他选项CREATE命令
）;
@覆盖
公共无效的onCreate（SQLiteDatabase数据库）{
database.execSQL（SQL_CREATE_SPECIAL_DAYS）;
}
@覆盖
公共无效onUpgrade（SQLiteDatabase分贝，INT oldVersion，诠释静态网页）{
Log.w（MySQLiteHelper.class.getName（），
+ oldVersion +到从版本升级数据库
+动态网页+，这将销毁所有旧数据）;
db.execSQL（DROP TABLE IF EXISTS+ dbFields.TABLE_NAME_SPECIAL_DAYS）;
的onCreate（DB）;
}
解决方案
通过
cursor.moveToFirst（）;
int值= cursor.getColumnIndex（根据MyColumn）;
您正在假定 PRAGMA 将返回所有列在一行。这就是现在它是如何工作的。从 PRAGMA 文件
那么，你的 doesColumnExist（）的方法应该是这个样子
布尔doesExist = FALSE;
光标光标= database.rawQuery（杂table_info（+为myTable +），NULL）;
而（cursor.moveToNext（））{
如果（cursor.getString（cursor.getColumnIndex（名字））。等于（根据MyColumn））{
doesExist = TRUE;
打破;
}
}
cursor.close（）;
返回doesExist;
另外，不要忘了关闭光标秒。
When inserting temporary values to all of the columns in my table, it appears to work. See method below and log below. But when I test if the column exists with my test method below, it returns a false that the column exists!!
The first snippet of code shows from where the temporary values and the method for testing if a column exists is called. The snippets below include the log, how the table is created, and the called methods. Thank you!
ContentValues values = setContVal_All_Columns(myTable);
//create row
long insertId = database.insert(myTable, null, values);
System.out.println("Column date exists = " + String.valueOf(doesColumnExist(myTable,"date")));
setContVal_All_Columns Method:
//sets generic content values to initialize row = excluding ID column
private ContentValues setContVal_All_Columns(String myTable) {
ContentValues contentValues = new ContentValues();
Cursor cursor = database.query(myTable,null,null,null,null,null,null);
String[] columnNames = cursor.getColumnNames();
cursor.moveToFirst();
for(String name : columnNames) {
if(!name.equals(IdColumn)) { //excludes Id column
int index = cursor.getColumnIndex(name);
System.out.println("Column name = " + name + " index = " + String.valueOf(index));
System.out.println("Type = " + String.valueOf(cursor.getType(index))); //appears to crash on the getType
if (cursor.getType(index) == 3) { //String
System.out.println("Column is string");
contentValues.put(name, " ");
} else if (cursor.getType(index) == 1) { //integer
contentValues.put(name, 0);
}
}
}
return contentValues;
}
METHOD FOR TESTING IF COLUMN EXISTS: always returning -1 on date column...
private boolean doesColumnExist(String myTable, String myColumn) {
boolean doesExist = true;
Cursor cursor = database.rawQuery("PRAGMA table_info(" + myTable + ")",null);
cursor.moveToFirst();
int value = cursor.getColumnIndex(myColumn);
if(value == -1)
{
doesExist = false;
}
return doesExist;
}
LOG INFO:
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column name = date index = 1
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Type = 0
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column name = name index = 2
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Type = 3
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column is string
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column name = altitude index = 3
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Type = 0
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column name = is_used index = 4
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Type = 0
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column name = warning index = 5
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Type = 0
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column name = action index = 6
02-16 19:58:42.296 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Type = 0
02-16 19:58:42.316 9711-9711/com.mycompany.dudesmyreminders I/System.out﹕ Column date exists = false
Table Creation Method:
//Database creation sql statement
private static final String SQL_CREATE_SPECIAL_DAYS =
"CREATE TABLE " + dbFields.TABLE_NAME_SPECIAL_DAYS + " (" +
dbFields.COLUMN_SPECIAL_DAYS_ID + INTEGER_PRIMARY_KEY + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_DATE + TEXT_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_NAME + TEXT_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_ALTITUDE + INTEGER_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_USED + INTEGER_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_WARNING + INTEGER_TYPE + COMMA_SEP +
dbFields.COLUMN_SPECIAL_DAYS_ACTION + INTEGER_TYPE +
// Any other options for the CREATE command
" )";
@Override
public void onCreate(SQLiteDatabase database) {
database.execSQL(SQL_CREATE_SPECIAL_DAYS);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(MySQLiteHelper.class.getName(),
"Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS " + dbFields.TABLE_NAME_SPECIAL_DAYS);
onCreate(db);
}
解决方案
With
cursor.moveToFirst();
int value = cursor.getColumnIndex(myColumn);
You're assuming that PRAGMA would return all the columns in a single row. That's now how it works. From the PRAGMA documentation
So, your doesColumnExist() method should look something like
boolean doesExist = false;
Cursor cursor = database.rawQuery("PRAGMA table_info(" + myTable + ")",null);
while (cursor.moveToNext()) {
if (cursor.getString(cursor.getColumnIndex("name")).equals(myColumn)) {
doesExist = true;
break;
}
}
cursor.close();
return doesExist;
Also, do not forget to close your Cursors.
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