SQLiteDatabase: Insert only if the value does not exist (not via raw SQL command)

SQLiteDatabase: Insert Only If Value Does Not Exist

Introduction

This article explores various techniques for inserting data into an SQLiteDatabase only if the value doesn’t already exist, avoiding redundant entries. We’ll delve into methods beyond raw SQL commands, emphasizing a cleaner and more efficient approach.

Using `insertWithOnConflict()`

The `insertWithOnConflict()` method is the most straightforward way to handle this scenario. It allows you to specify the desired conflict resolution strategy. Here’s an example:

ContentValues values = new ContentValues();
values.put("name", "John Doe");
values.put("age", 30);

long rowId = db.insertWithOnConflict("users", null, values, SQLiteDatabase.CONFLICT_IGNORE);
if (rowId == -1) {
  // Row already exists.
} else {
  // Row inserted successfully.
}

In this example, `CONFLICT_IGNORE` instructs the database to ignore the insert if a conflict occurs (i.e., the row already exists). If the insertion is successful, `rowId` will be greater than -1. Otherwise, it will be -1, indicating a conflict.

Using `insertOrThrow()` with `checkConflict()`

Alternatively, you can use the `insertOrThrow()` method in conjunction with a custom conflict checking function:

boolean insertIfNotExist(SQLiteDatabase db, String tableName, ContentValues values) {
  try {
    db.insertOrThrow(tableName, null, values);
    return true; // Row inserted successfully
  } catch (SQLiteConstraintException e) {
    // Handle conflict here (e.g., update existing row if necessary)
    return false; // Row already exists
  }
}

This approach defines a utility function `insertIfNotExist()`. It attempts to insert the data using `insertOrThrow()`. If a `SQLiteConstraintException` is caught, it indicates a conflict, and you can either handle the conflict (e.g., update the existing row) or simply return `false`.

Comparing Approaches

Here’s a comparison of the two methods:

Choosing the Right Approach

The choice between these methods depends on your specific needs. If you simply want to ignore conflicts, `insertWithOnConflict()` provides a convenient solution. If you require more control over conflict resolution or need to handle specific conflict scenarios, `insertOrThrow()` with a custom conflict checking function offers greater flexibility.