Android SQLite 如何在一個方法實現插入或更新
https://stackoverflow.com/questions/13311727/android-sqlite-insert-or-update
I believe that you are asking how toINSERT new rows or UPDATE your existing rowsin one step. While that is possible in a single raw SQL as discussed inthis answer, I found that it easier to do this in two steps in Android usingSQLiteDatabase.insertWithOnConflict()
ContentValues initialValues = new ContentValues();
initialValues.put("_id", 1); // the execution is different if _id is 2
initialValues.put("columnA", "valueNEW");
int id = (int) yourdb.insertWithOnConflict("your_table", null, initialValues, SQLiteDatabase.CONFLICT_IGNORE);
if (id == -1) {
yourdb.update("your_table", initialValues, "_id=?", new String[] {"1"}); // number 1 is the _id here, update to variable for your code
}
This example assumes that the table key is set for column "_id", that you know the record _id, and that there is already row #1 (_id=1, columnA = "valueA", columnB = "valueB"). Here is the difference using insertWithOnConflict with CONFLICT_REPLACE and CONFLICT_IGNORE
- CONFLICT_REPLACE will overwrite existing values in other columns to null (ie. columnB will become NULL and the result will be _id=1, columnA = "valueNEW", columnB = NULL). You lose existing data as result and I do not use it in my code.
- CONFLICT_IGNORE will skip the SQL INSERT for your existing row #1 and you will SQL UPDATE this row in the next step preserving the content of all other columns (ie. the result will be _id=1, columnA = "valueNEW", columnB = "valueB").
When you attempt to insert new row #2 which does not exist yet, the code will only execute the SQL INSERT in the first statement insertWithOnConflict (ie. the result will be _id=2, columnA = "valueNEW", columnB = NULL).
Beware ofthis bugwhich is causing SQLiteDatabase.CONFLICT_IGNORE to malfunction on API10 (and probably API11). The query is returning 0 instead of -1 when I test on Android 2.2.
If you do not know the record key _id or you have a condition that will not create a conflict, you canreverse the logic to UPDATE or INSERT. This will keep your record key _id during UPDATE or create a new record _id during INSERT.
int u = yourdb.update("yourtable", values, "anotherID=?", new String[]{"x"});
if (u == 0) {
yourdb.insertWithOnConflict("yourtable", null, values, SQLiteDatabase.CONFLICT_REPLACE);
}
The above example assumes that your just want to UPDATE timestamp value in the record for example. If you call insertWithOnConflict first, INSERT will create new record _id due to the difference in the timestamp condition.