value - sqlite rename table




How do I rename a column in a SQLite database table? (9)

I would need to rename a few columns in some tables in a SQLite database. I know that a similar question has been asked on stackoverflow previously, but it was for SQL in general, and the case of SQLite was not mentioned.

From the SQLite documentation for ALTER TABLE, I gather that it's not possible to do such a thing "easily" (i.e. a single ALTER TABLE statement).

I was wondering someone knew of a generic SQL way of doing such a thing with SQLite.


change table column < id > to < _id >

 String LastId = "id";

    database.execSQL("ALTER TABLE " + PhraseContract.TABLE_NAME + " RENAME TO " + PhraseContract.TABLE_NAME + "old");
    database.execSQL("CREATE TABLE " + PhraseContract.TABLE_NAME
    +"("
            + PhraseContract.COLUMN_ID + " INTEGER PRIMARY KEY,"
            + PhraseContract.COLUMN_PHRASE + " text ,"
            + PhraseContract.COLUMN_ORDER  + " text ,"
            + PhraseContract.COLUMN_FROM_A_LANG + " text"
    +")"
    );
    database.execSQL("INSERT INTO " +
            PhraseContract.TABLE_NAME + "("+ PhraseContract.COLUMN_ID +" , "+ PhraseContract.COLUMN_PHRASE + " , "+ PhraseContract.COLUMN_ORDER +" , "+ PhraseContract.COLUMN_FROM_A_LANG +")" +
            " SELECT " + LastId +" , "+ PhraseContract.COLUMN_PHRASE + " , "+ PhraseContract.COLUMN_ORDER +" , "+ PhraseContract.COLUMN_FROM_A_LANG +
            " FROM " + PhraseContract.TABLE_NAME + "old");
    database.execSQL("DROP TABLE " + PhraseContract.TABLE_NAME + "old");

From the official documentation

A simpler and faster procedure can optionally be used for some changes that do no affect the on-disk content in any way. The following simpler procedure is appropriate for removing CHECK or FOREIGN KEY or NOT NULL constraints, renaming columns, or adding or removing or changing default values on a column.

  1. Start a transaction.

  2. Run PRAGMA schema_version to determine the current schema version number. This number will be needed for step 6 below.

  3. Activate schema editing using PRAGMA writable_schema=ON.

  4. Run an UPDATE statement to change the definition of table X in the sqlite_master table: UPDATE sqlite_master SET sql=... WHERE type='table' AND name='X';

    Caution: Making a change to the sqlite_master table like this will render the database corrupt and unreadable if the change contains a syntax error. It is suggested that careful testing of the UPDATE statement be done on a separate blank database prior to using it on a database containing important data.

  5. If the change to table X also affects other tables or indexes or triggers are views within schema, then run UPDATE statements to modify those other tables indexes and views too. For example, if the name of a column changes, all FOREIGN KEY constraints, triggers, indexes, and views that refer to that column must be modified.

    Caution: Once again, making changes to the sqlite_master table like this will render the database corrupt and unreadable if the change contains an error. Carefully test of this entire procedure on a separate test database prior to using it on a database containing important data and/or make backup copies of important databases prior to running this procedure.

  6. Increment the schema version number using PRAGMA schema_version=X where X is one more than the old schema version number found in step 2 above.

  7. Disable schema editing using PRAGMA writable_schema=OFF.

  8. (Optional) Run PRAGMA integrity_check to verify that the schema changes did not damage the database.

  9. Commit the transaction started on step 1 above.


As mentioned before, there is a tool SQLite Database Browser, which does this. Lyckily, this tool keeps a log of all operations performed by the user or the application. Doing this once and looking at the application log, you will see the code involved. Copy the query and paste as required. Worked for me. Hope this helps


Create a new column with the desired column name: COLNew.

ALTER TABLE {tableName} ADD COLUMN COLNew {type};

Copy contents of old column COLOld to new column COLNew.

INSERT INTO {tableName} (COLNew) SELECT {COLOld} FROM {tableName}

Note: brackets are necessary in above line.


One option, if you need it done in a pinch, and if your initial column was created with a default, is to create the new column you want, copy the contents over to it, and basically "abandon" the old column (it stays present, but you just don't use/update it, etc.)

ex:

alter table TABLE_NAME ADD COLUMN new_column_name TYPE NOT NULL DEFAULT '';
update TABLE_NAME set new_column_name = old_column_name;
update TABLE_NAME set old_column_name = ''; -- abandon old column, basically

This leaves behind a column (and if it was created with NOT NULL but without a default, then future inserts that ignore it might fail), but if it's just a throwaway table, the tradeoffs might be acceptable. Otherwise use one of the other answers mentioned here, or a different database that allows columns to be renamed.


Quoting the sqlite documentation:

SQLite supports a limited subset of ALTER TABLE. The ALTER TABLE command in SQLite allows the user to rename a table or to add a new column to an existing table. It is not possible to rename a colum, remove a column, or add or remove constraints from a table.

What you can do of course is, create a new table with the new layout, SELECT * FROM old_table, and fill the new table with the values you'll receive.


Say you have a table and need to rename "colb" to "col_b":

First you rename the old table:

ALTER TABLE orig_table_name RENAME TO tmp_table_name;

Then create the new table, based on the old table but with the updated column name:

CREATE TABLE orig_table_name (
  col_a INT
, col_b INT
);

Then copy the contents across from the original table.

INSERT INTO orig_table_name(col_a, col_b)
SELECT col_a, colb
FROM tmp_table_name;

Lastly, drop the old table.

DROP TABLE tmp_table_name;

Wrapping all this in a BEGIN TRANSACTION; and COMMIT; is also probably a good idea.


This was just fixed with 2018-09-15 (3.25.0)

Enhancements the ALTER TABLE command:

  • Add support for renaming columns within a table using ALTER TABLE table RENAME COLUMN oldname TO newname.
  • Fix table rename feature so that it also updates references to the renamed table in triggers and views.

You can find the new syntax documented under ALTER TABLE

The RENAME COLUMN TO syntax changes the column-name of table table-name into new-column-name. The column name is changed both within the table definition itself and also within all indexes, triggers, and views that reference the column. If the column name change would result in a semantic ambiguity in a trigger or view, then the RENAME COLUMN fails with an error and no changes are applied.

Image source: https://www.sqlite.org/images/syntax/alter-table-stmt.gif


sqlite3 yourdb .dump > /tmp/db.txt
edit /tmp/db.txt change column name in Create line
sqlite2 yourdb2 < /tmp/db.txt
mv/move yourdb2 yourdb





alter-table