Sqlite Select Where Empty

SQLite select where empty?

There are several ways, like:

where some_column is null or some_column = ''

or

where ifnull(some_column, '') = ''

or

where coalesce(some_column, '') = ''

of

where ifnull(length(some_column), 0) = 0

Android sqlite - select records where field is null or empty

Try

cursor = db.query(DBHelper.TABLE_NAME, COLUMNS, "folder_name is null or folder_name = ?", new String[] {""}, null, null, DBHelper.TIMESTAMP_COL + " DESC");

Check if table is empty in SQLite

Yo can use:

SELECT EXISTS (SELECT 1 FROM my_table);

this will return 1 row with 1 column which will be 0 if the table is empty or 1 if it contains any rows.

EXISTS will return as soon as it finds the 1st row in the table and it will not scan the whole table.

Android SQLite query where column is not null and not empty

I believe the correct syntax would be:

AND key IS NOT NULL AND key != ""

where key is your column

SQlite select returns (null) instead of for empty values

Using snprintf to compose an SQL query in this way is bad not only because of the nulls, but also because you might run into all kinds of trouble due to the fact that you're not escaping your strings.

I'd suggest using the prepared statements API instead. When you use that, at the C level you'd have to explicitely set some is_bool flag according to whether a given value is NULL or not.

sqlite3 select from empty table = no select?

It's a bit different.

When using SELECT with rows, ifnull() is evaluated once per row, so you need at least one row.

You could probably try something:

SELECT IFNULL((SELECT _id FROM empty_table LIMIT 1), 1)

How to set all values in a column to empty (null)?

Just ignore the WHERE clause would do the trick. How to change a value in a column on a SQLite database?

UPDATE table_name SET column_name = NULL

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