Once again, still perplexed as to why these issues remain after all these years.Īnd again, thanks to everyone for their input - invaluable. I think I will redesign the table structure, eliminate the auto increment key column, and use a CHAR variable containing the name for the key, relying on the database to replace (CASCADE) any changes made to the key to the other tables referenced if required. Note: Keep the default LockingModelmExclusive and. I understand there is passion both ways, to use or not to use. The database connection unlocks the database file at the conclusion of each read or write transaction. I guess it throws me back into the surrogate key debate. I don't understand why others don't run into this problem (or why Appeon doesn't address it - seems like it was at one time by using the Identity Column on the Update Properties menu). What surprises me is that this is an age old issue going back over a decade or more. Locking the table first would work but not sure if this would lead to a performance issue. Selecting Max identity is dicey, someone else can insert and in the meantime. Unfortunately, it has to appear immediately after the INSERT statement semicolon and PB doesn't allow that. MySQL does provide a method for retrieving the latest insert id, SELECT LAST_INSERT_ID(). We have to change database version if we have added a new row in the database table in this case if we have requirement that we dont want to lost existing data. Then it will insert all of the data from the _employees_old table into the employees table.I'm on the latest version of PB, also in development so all of the PFODBxxx.Ini files are there. SQLite AUTOINCREMENT is a keyword used for auto incrementing a value of a field in the table.You do not need ID1. Then it will create the new employees table with the hire_date field called start_date. This example will rename our existing employees table to _employees_old. INSERT INTO employees (employee_id, last_name, first_name, start_date) Let's look at an example that shows how to rename a column in a SQLite table.Īnd we wanted to rename the hire_date field to start_date, we could do the following: PRAGMA foreign_keys=off The syntax to RENAME A COLUMN in a table in SQLite is: PRAGMA foreign_keys=off 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. SELECT employee_id, last_name, first_name INSERT INTO employees (employee_id, last_name, first_name) 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 With AUTOINCREMENT, the values are stored in a separate table and. You can not use the ALTER TABLE statement to drop a column in a table. The first answer (still below) only works without an AUTOINCREMENT for id. 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 Step 4: Creating a new Java class for performing SQLite operations. You can not use the ALTER TABLE statement to modify a column in SQLite.
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