How Can I Safely Remove a Column from an SQLite Table While Preserving Data?

How to safely delete columns in SQLite table while retaining data?

The user tried to delete a column from a SQLite table using the SQL statement "ALTER TABLE table_name DROP COLUMN column_name" but encountered a problem. This article will introduce the alternatives recommended in the SQLite documentation to solve this problem and ensure data security.

SQLite has limited support for ALTER TABLE operations, allowing only adding new columns or changing table names. For more complex structural changes, SQLite recommends rebuilding the table. An effective solution is to temporarily store the data, rebuild the table, and then restore the data.

For example, assume table "t1" contains columns "a", "b", and "c". To delete column "c", you can follow these steps:

<code class="language-sql">BEGIN TRANSACTION;
CREATE TEMPORARY TABLE t1_backup(a,b);
INSERT INTO t1_backup SELECT a,b FROM t1;
DROP TABLE t1;
CREATE TABLE t1(a,b);
INSERT INTO t1 SELECT a,b FROM t1_backup;
DROP TABLE t1_backup;
COMMIT;</code>

With these steps, you can safely delete columns while maintaining the integrity of your SQLite table data.

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