Instead you will need to rename the table, create a new table, and copy the data into the new table. You can not use the ALTER TABLE statement to rename a column in SQLite. Then it will insert all of the data (excluding the hire_date field) from the _employees_old table into the employees table. Then it will create the new employees table with the hire_date field removed.
This example will rename our existing employees table to _employees_old. SELECT employee_id, last_name, first_name INSERT INTO employees (employee_id, last_name, first_name)
#Deleting column in db sqlite how to
Let's look at an example that shows how to drop a column in a SQLite table.įor example, if we had an employees table that was defined as follows: CREATE TABLE employeesĪnd we wanted to drop the column called hire_date, we could do the following: PRAGMA foreign_keys=off The syntax to DROP A COLUMN in a table in SQLite is: PRAGMA foreign_keys=off You can not use the ALTER TABLE statement to drop a column in a table.
Then it will insert all of the data from the _employees_old table into the employees table. Then it will create the new employees table with the last_name field defined as a VARCHAR datatype. SELECT employee_id, last_name, first_name, hire_date INSERT INTO employees (employee_id, last_name, first_name, hire_date)
( employee_id INTEGER PRIMARY KEY AUTOINCREMENT,Īnd we wanted to change the datatype of the last_name field to VARCHAR, we could do the following: PRAGMA foreign_keys=off ĪLTER TABLE employees RENAME TO _employees_old Let's look at an example that shows how to modify a column in a SQLite table.įor example, if we had an employees table that had a column called last_name that was defined as a CHAR datatype: CREATE TABLE employees The syntax to MODIFY A COLUMN in a table in SQLite is: PRAGMA foreign_keys=off ĪLTER TABLE table1 RENAME TO _table1_old Now you should have a sqlite_sequence table.You can not use the ALTER TABLE statement to modify a column in SQLite. Since we don't need the dummy table we can go ahead and delete it right after. This should create the dummy table as well as the sqlite_sequence table. To do this we will create a dummy table with an AUTOINCREMENT column. The error hints at sqlite_sequence not existing so we need to create it.īut since we can't create one using the CREATE command, we will have to trigger one to be created. There are other DB actions like changing the schema of the AUTOINCREMENT column that could lead to this error as well. So when you attempt to drop a table, for example, SQLite will also attempt to delete the entry for that table in the sqlite_sequence table which will lead to the no such table: sqlite_sequence error if the sqlite_sequence table was never created. So for example, when you convert a MySQL database to SQLite your AUTOINCREMENT field may not be transferred over and hence SQLite will not create the sqlite_sequence table because there are no AUTOINCREMENT columns to keep track of. The only thing you cannot do is to create the sqlite_sequence using the CREATE command.Īlso, it's advised not to mess with the entries as the table is used by the database engine.īy default your database will not have the sqlite_sequence table, It's only created the first time you create a new table with an AUTOINCREMENT column. It's a table like the one you create yourself which means you can UPDATE, INSERT, and, DELETE entries like you would any table. The sqlite_sequence table keeps track of AUTOINCREMENT columns for tables you create. 👉 What is the sqlite_sequence table for? I have clients looking for freelance developers
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