Use the ALTER TABLE statement with the DROP COLUMN clause.Because dropping a column from a table is a pending change to the definition of the table, the table space is placed in advisory REORG-pending status (AREOR). When the pending change is applied (by running the REORG utility with the SHRLEVEL CHANGE or REFERENCE options), the column is dropped from the table, and any dependent packages and statements in the dynamic statement cache are invalidated.
The DELETE statement is used to delete rows from a table. If you want to remove a specific row from a table you should use WHERE condition.
But if you do not specify the WHERE condition it will remove all the rows from the table.
There are some more terms similar to DELETE statement like as DROP statement and TRUNCATE statement but they are not exactly same there are some differences between them.
Difference between DELETE and TRUNCATE statements
There is a slight difference b/w delete and truncate statement. The DELETE statement only deletes the rows from the table based on the condition defined by WHERE clause or delete all the rows from the table when condition is not specified.
But it does not free the space containing by the table.
The TRUNCATE statement: it is used to delete all the rows from the table and free the containing space.
Let's see an "employee" table.
Emp_idNameAddressSalary1AryanAllahabad220002ShurabhiVaranasi130003PappuDelhi24000Execute the following query to truncate the table:
Difference b/w DROP and TRUNCATE statements
When you use the drop statement it deletes the table's row together with the table's definition so all the relationships of that table with other tables will no longer be valid.
When you drop a table:
- Table structure will be dropped
- Relationship will be dropped
- Integrity constraints will be dropped
- Access privileges will also be dropped
On the other hand when we TRUNCATE a table, the table structure remains the same, so you will not face any of the above problems.
Which command in SQL is used to delete a table entire data and structure Mcq?
Explanation: TRUNCATE command is used to delete all rows and free up space from a table.
Which SQL statement is used to delete entire data and structure?
The DELETE statement is used to delete existing records in a table.