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The SQL statements for erasing the data kept in a table include the TRUNCATE and DELETE statements. When records or rows in a table are no longer required, deletion procedures are performed on them. Each entry in the table removed using the DELETE command has a condition applied before it. In other words, you can simultaneously delete one or more rows. The TRUNCATE command, however, simultaneously deletes every row from the table.
Due to the similarities in their functions, the DROP and TRUNCATE statements are SQL commands that are frequently used interchangeably. This response seeks to clarify the distinctions between these claims and the ideal situations to apply.
What is a Drop statement?
A DDL (Data Definition Language) command called DROP is used to delete a table’s definition, indexes, data, constraints, triggers, etc. Performance-wise, the DROP command is quicker than TRUNCATE but takes longer to complete due to the problems it causes.
Contrary to DELETE, we cannot undo the effects of the DROP command on the data.
Table space is released from memory via the DROP command because the table and its contents are permanently deleted.
A DDL Command is DROP. The deletion of an object with the DROP command is irreversible and cannot be undone. The DROP command removes the table’s whole conceptual model from the database in contrast to TRUNCATE, which just purges the data from the tables.
How does DROP TABLE work?
The DROP TABLE procedure deletes the table definition, data, associated triggers, constraints, and indexes. This command frees the memory space. When the DROP TABLE command is used, no triggers are triggered. This operation can be undone in Oracle, SQL Server, and PostgreSQL but not MySQL.
DROP TABLE in SQL Server requires the ALTER authority in the schema to which the table belongs; DROP in MySQL and DROP ANY TABLE in Oracle. Users of PostgreSQL can delete their tables.
What is a Truncate statement?
A DDL (Data Definition Language) command is TRUNCATE. The entire contents of the table’s tuples are removed using it. The TRUNCATE command lacks a WHERE clause, similar to the DROP command. Compared to the DROP and DELETE commands, the TRUNCATE command is quicker. We cannot roll the data after employing this command, just like the DROP command.
Truncate is a DDL operation since it alters the data definition to re-initialize the identity, as opposed to Delete, which merely removes the records from the database without altering the definition. It is DML for this reason. Similar to naming a table and adding some initial records.
How does TRUNCATE TABLE work?
When using this command, use caution. Unlike MySQL and Oracle, TRUNCATE transactions can be undone in databases like SQL Database and PostgreSQL. TRUNCATE removes records without first scanning them, making it faster than DELETE. To remove data from a table, TRUNCATE TABLE locks the entire table; as a result, this command requires less transaction space than DELETE. In contrast to DELETE, TRUNCATE does not report how many rows were removed from the table.
Additionally, the table auto-increment value is reset to zero. If you add a record after the table has been truncated, its ID will be 1. Restarting or continuing the auto-increment value is an option in PostgreSQL. Oracle increments values using a sequence; TRUNCATE does not reset this sequence.
You must have the authorisation to utilise the TRUNCATE TABLE, of course.
You require the TRUNCATE privilege in PostgreSQL, the ALTER table permission in SQL Server, and the DROP privilege in MySQL. Finally, to use this command, Oracle needs the DROP ANY TABLE system privilege.
Differences between the SQL commands DROP and TRUNCATE:
| Drop | Truncate |
| The table definition, and its contents can be deleted using the DROP command. | To remove every record from a table, use the TRUNCATE command. |
| The DROP command releases memory-based table space. | At the same time, the table space is not freed from memory by the TRUNCATE command. |
| A DDL (Data Definition Language) instruction is called “DROP.” | In contrast, the DDL (Data Definition Language) command TRUNCATE is also available. |
| There is no visibility of the table in the DROP command. | There is a view of the table while in this command. |
| The DROP command will lift integrity limitations. | Integrity limitations won’t be lifted while in this command. |
| The undo space is not used in the DROP command. | Undo space is consumed during this command, but less so than DELETE. |
