db.execSQL("CREATE TABLE " +DBTable0+ "("+ROW2+" INTEGER PRIMARY KEY AUTOINCREMENT, "+ROW3+" VARCHAR NOT NULL, "+ROW0+" TEXT NOT NULL, "+ROW1+" VARCHAR NOT NULL)");
这是我的数据库的创建表命令。
我想重置ROW2的值。
例如,我在此表上有5条记录。
1,save1,这是一个Save1,11.25
2,save2,这是一个Save2,23.48
3,save3,这是一个Save3,09.45
4,save4,这是一个Save4,11.55
5,保存5,这是保存5,21.00
我要删除save2。当我删除它或其他删除时,我想重置ROW2索引,所以
1,save1,这是一个Save1,11.25
2,save3,这是一个Save3,09.45
3,save4,这是一个Save4,11.55
4,save5,这是一个Save5,21.00
像这样 ...
我该怎么办。?
最佳答案
要在使用AUTOINCREMENT时重置为补偿已删除行而分配的rowid,您必须进行两项更改:
您将不得不更改(更新)行ID或每行的行ID的别名(不按顺序排列),以遵循新的顺序,并且
那么您将不得不将系统表sqlite_sequence中的相应行更改(更新)为分配的最高rowid。
这是绝对不建议的,并且将大大增加使用AUTOINCREMENT的效率(当您很有可能不需要使用AUTOINCREMENT时)。
SQLite Autoincrement包括
AUTOINCREMENT关键字强加了额外的CPU,内存,磁盘空间和磁盘I / O开销,如果没有严格要求,则应避免使用。通常不需要。
实际上,永远不要将rowid
依赖于SQlite分配的任何内容
(<column_name> INTEGER PRIMARY KEY
(带有或不带有AUTOINCREMENT)使rowid成为别名。
你说 :-
我想重置ROW2的值。
我建议重新评估您的意愿,仅在实际上有需要的情况下才想要,但实际上没有。
然后你说
我将通过ListViews选择记录。然后,我可以删除和更新所选项目上的记录。因此,当我删除中间的任何记录时。 ID混合并删除错误记录
如果您使用CursorAdapter,例如SimpleCursorAdapter是onItemClick和onItemLongClick的第四个参数。
请注意,要使用CursorAdapter,必须在名为Listid的Cursor中存在名为_id的列,并且该列应包含行ID。您可以使用BaseColumns._ID,它是一个值为_id的常量。
通常,您将表中的列定义为_id INTEGER PRIMARY KEY
或者,您可以使用rowid AS _id, *
,在这种情况下,列_id将附加到所有其他列。
可以找到此和其他适配器的其他选项/植入物here
工作实例
但是,如果您坚持要求,那么以下示例可以满足我的要求。
请注意,此示例对2个表执行相同(有效)的操作。
第一个表table1使用AUTOINCREMENT
第二个表table2没有进行AUTOINCREMENT编码,但是结果是相同的(除了sqlite_sequence之外,没有修改,因为sqlite_sequence中没有行,因为AUTOINCREMENT也没有被编码)。
主要代码在数据库帮助程序(SQLiteOpenHelper的子类)中,即DBHelper.java:
public class DBHelper extends SQLiteOpenHelper {
public static final String DBNAME = "mydb";
public static final int DBVERSION = 1;
public static final String TBL_TABLE1 = "table1";
public static final String TBL_TABLE2 = "table2";
public static final String COL_TABLE_COL1 = "col1";
public static final String COL_TABLE_COL2 = "col2";
public static final String COL_TABLE_COL3 = "col3";
private static final String crt_table1_sql = "CREATE TABLE IF NOT EXISTS " + TBL_TABLE1 + "(" +
COL_TABLE_COL1 + " INTEGER PRIMARY KEY AUTOINCREMENT," +
COL_TABLE_COL2 + " TEXT NOT NULL," +
COL_TABLE_COL3 + " TEXT NOT NULL" +
")";
private static final String crt_table2_sql = "CREATE TABLE IF NOT EXISTS " + TBL_TABLE2 + "(" +
COL_TABLE_COL1 + " INTEGER PRIMARY KEY," +
COL_TABLE_COL2 + " TEXT NOT NULL," +
COL_TABLE_COL3 + " TEXT NOT NULL" +
")";
SQLiteDatabase mDB;
public DBHelper(Context context) {
super(context, DBNAME, null, DBVERSION);
mDB = this.getWritableDatabase();
}
@Override
public void onConfigure(SQLiteDatabase db) {
super.onConfigure(db);
db.disableWriteAheadLogging();
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(crt_table1_sql);
db.execSQL(crt_table2_sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int i, int i1) {
}
public void insert(String col2, String col3) {
ContentValues cv = new ContentValues();
cv.put(COL_TABLE_COL2,col2);
cv.put(COL_TABLE_COL3,col3);
mDB.beginTransaction();
mDB.insert(TBL_TABLE1,null,cv);
mDB.insert(TBL_TABLE2,null,cv);
mDB.setTransactionSuccessful();
mDB.endTransaction();
}
public void deleteByValues(String col2, String col3) {
String whereclause = COL_TABLE_COL2 + "=? AND " + COL_TABLE_COL3 + "=?";
String[] args = new String[]{col2,col3};
mDB.beginTransaction();
mDB.delete(TBL_TABLE1,whereclause,args);
mDB.delete(TBL_TABLE2,whereclause,args);
rationaliseCol1Values();
mDB.setTransactionSuccessful();
mDB.endTransaction();
}
private void rationaliseCol1Values() {
ContentValues cv = new ContentValues();
Cursor csr = mDB.query(TBL_TABLE1,null,null,null,null,null,COL_TABLE_COL1 + " ASC");
int rowcount = csr.getCount();
long expected_id = 1;
long current_id;
String where_clause = COL_TABLE_COL1 + "=?";
String[] args = new String[1];
while (csr.moveToNext()) {
current_id = csr.getLong(csr.getColumnIndex(COL_TABLE_COL1));
if (current_id != expected_id) {
cv.clear();
cv.put(COL_TABLE_COL1,expected_id);
args[0] = String.valueOf(current_id);
mDB.update(TBL_TABLE1,cv,where_clause,args);
mDB.update(TBL_TABLE2,cv,where_clause,args);
}
expected_id++;
}
// Now adjust sqlite_sequence
where_clause = "name=?";
args[0] = TBL_TABLE1;
cv.clear();
cv.put("seq",String.valueOf(rowcount));
mDB.update("sqlite_sequence",cv,where_clause,args);
}
public void logTableRows(int stage) {
String tablenamne_column = "tablename";
Cursor[] csr = new Cursor[] {
mDB.query(TBL_TABLE1,new String[]{"'table1' AS " + tablenamne_column + ",*"},null,null,null,null,null),
mDB.query(TBL_TABLE2,new String[]{"'table2' AS " + tablenamne_column + ",*"}, null,null,null,null,null)
};
MergeCursor csr3 = new MergeCursor(csr);
StringBuilder sb = new StringBuilder("Data in both tables consists of " + String.valueOf(csr3.getCount()) + " rows :-");
while (csr3.moveToNext()) {
sb.append(
"\n\tTableName = " + csr3.getString(csr3.getColumnIndex(tablenamne_column)
)
).append(" " + COL_TABLE_COL1 + " value is " + csr3.getString(csr3.getColumnIndex(COL_TABLE_COL1))
).append(" " + COL_TABLE_COL2 + " value is " + csr3.getString(csr3.getColumnIndex(COL_TABLE_COL2))
).append(" " + COL_TABLE_COL3 + " value is" + csr3.getString(csr3.getColumnIndex(COL_TABLE_COL3))
);
}
Log.d("DATA4STAGE" + String.valueOf(stage),sb.toString());
}
}
Rowid的核心操作(因此也就是COL1)是通过合理化的Col1Values()方法进行的。它本身作为deleteByValues方法的一部分被调用。
如果有根据id又名COL1删除的方法,那么这也将调用RationaliseCol1Values()方法)。
仅存在logTableRows,以便可以将表输出到日志。
用于测试上述内容的调用活动是:
public class MainActivity extends AppCompatActivity {
DBHelper mDBHlpr;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDBHlpr = new DBHelper(this);
manipulateSomeData();
}
private void manipulateSomeData() {
mDBHlpr.logTableRows(0);
mDBHlpr.insert("TEST001","TESTING001");
mDBHlpr.insert("TEST002","TESTING001");
mDBHlpr.insert("TEST003","TESTING001");
mDBHlpr.insert("TEST004","TESTING001");
mDBHlpr.insert("TEST005","TESTING001");
mDBHlpr.insert("TEST006","TESTING001");
mDBHlpr.insert("TEST007","TESTING001");
mDBHlpr.insert("TEST008","TESTING001");
mDBHlpr.insert("TEST009","TESTING001");
mDBHlpr.logTableRows(1);
mDBHlpr.deleteByValues("TEST005","TESTING001");
mDBHlpr.logTableRows(2);
mDBHlpr.deleteByValues("TEST008","TESTING001");
mDBHlpr.logTableRows(3);
mDBHlpr.deleteByValues("TEST003","TESTIN001");
mDBHlpr.logTableRows(4);
}
}
这个 :-
列出行(首次运行时无)。
添加9行,其中COL2是唯一的(再次仅在首次运行时)。
列出所有9行(第一次运行)。
删除任何在COL2中具有值“ TEST005”而在COL3中具有值“ TESTING001”的行。
列出行(请注意如何维护COL1的序列)。
删除任何在COL2中具有“ TEST008”和在COL3中具有“ TESTING001”的值的行。
列出行(请注意如何维护COL1的序列)。
删除在COL2中具有值“ TEST003”而在COL3中具有值“ TESTIN001”的任何行。由于拼写错误(G缺失)
列出行(请注意如何维护COL1的序列)。
结果输出到日志为:
2018-12-31 12:43:21.618 2269-2269/so53976714.so53976714 D/DATA4STAGE0: Data in both tables consists of 0 rows :-
2018-12-31 12:43:21.657 2269-2269/so53976714.so53976714 D/DATA4STAGE1: Data in both tables consists of 18 rows :-
TableName = table1 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table1 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table1 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table1 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table1 col1 value is 5 col2 value is TEST005 col3 value isTESTING001
TableName = table1 col1 value is 6 col2 value is TEST006 col3 value isTESTING001
TableName = table1 col1 value is 7 col2 value is TEST007 col3 value isTESTING001
TableName = table1 col1 value is 8 col2 value is TEST008 col3 value isTESTING001
TableName = table1 col1 value is 9 col2 value is TEST009 col3 value isTESTING001
TableName = table2 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table2 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table2 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table2 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table2 col1 value is 5 col2 value is TEST005 col3 value isTESTING001
TableName = table2 col1 value is 6 col2 value is TEST006 col3 value isTESTING001
TableName = table2 col1 value is 7 col2 value is TEST007 col3 value isTESTING001
TableName = table2 col1 value is 8 col2 value is TEST008 col3 value isTESTING001
TableName = table2 col1 value is 9 col2 value is TEST009 col3 value isTESTING001
2018-12-31 12:43:21.666 2269-2269/so53976714.so53976714 D/DATA4STAGE2: Data in both tables consists of 16 rows :-
TableName = table1 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table1 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table1 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table1 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table1 col1 value is 5 col2 value is TEST006 col3 value isTESTING001
TableName = table1 col1 value is 6 col2 value is TEST007 col3 value isTESTING001
TableName = table1 col1 value is 7 col2 value is TEST008 col3 value isTESTING001
TableName = table1 col1 value is 8 col2 value is TEST009 col3 value isTESTING001
TableName = table2 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table2 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table2 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table2 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table2 col1 value is 5 col2 value is TEST006 col3 value isTESTING001
TableName = table2 col1 value is 6 col2 value is TEST007 col3 value isTESTING001
TableName = table2 col1 value is 7 col2 value is TEST008 col3 value isTESTING001
TableName = table2 col1 value is 8 col2 value is TEST009 col3 value isTESTING001
2018-12-31 12:43:21.675 2269-2269/so53976714.so53976714 D/DATA4STAGE3: Data in both tables consists of 14 rows :-
TableName = table1 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table1 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table1 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table1 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table1 col1 value is 5 col2 value is TEST006 col3 value isTESTING001
TableName = table1 col1 value is 6 col2 value is TEST007 col3 value isTESTING001
TableName = table1 col1 value is 7 col2 value is TEST009 col3 value isTESTING001
TableName = table2 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table2 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table2 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table2 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table2 col1 value is 5 col2 value is TEST006 col3 value isTESTING001
TableName = table2 col1 value is 6 col2 value is TEST007 col3 value isTESTING001
TableName = table2 col1 value is 7 col2 value is TEST009 col3 value isTESTING001
2018-12-31 12:43:21.681 2269-2269/so53976714.so53976714 D/DATA4STAGE4: Data in both tables consists of 14 rows :-
TableName = table1 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table1 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table1 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table1 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table1 col1 value is 5 col2 value is TEST006 col3 value isTESTING001
TableName = table1 col1 value is 6 col2 value is TEST007 col3 value isTESTING001
TableName = table1 col1 value is 7 col2 value is TEST009 col3 value isTESTING001
TableName = table2 col1 value is 1 col2 value is TEST001 col3 value isTESTING001
TableName = table2 col1 value is 2 col2 value is TEST002 col3 value isTESTING001
TableName = table2 col1 value is 3 col2 value is TEST003 col3 value isTESTING001
TableName = table2 col1 value is 4 col2 value is TEST004 col3 value isTESTING001
TableName = table2 col1 value is 5 col2 value is TEST006 col3 value isTESTING001
TableName = table2 col1 value is 6 col2 value is TEST007 col3 value isTESTING001
TableName = table2 col1 value is 7 col2 value is TEST009 col3 value isTESTING001
注意不建议使用以上方法