How can we create a temporary table in Oracle and insert data into it using the select statement?

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To create a temporary table in Oracle and insert data into it using the select statement, you can follow these steps:

1. Begin by logging in to Oracle using SQL Developer or SQL*Plus.

2. Use the CREATE GLOBAL TEMPORARY TABLE statement to create a temporary table. You need to specify the column names and data types for the temporary table. For example:

   CREATE GLOBAL TEMPORARY TABLE temp_table ( id NUMBER, name VARCHAR2(50) ) ON COMMIT PRESERVE ROWS;

   In this example, the temporary table is named "temp_table", and it has two columns: "id" of type NUMBER and "name" of type VARCHAR2.

   The "ON COMMIT PRESERVE ROWS" clause ensures that the data in the temporary table is not deleted when the transaction is committed.

3. Use the INSERT INTO SELECT statement to insert data into the temporary table using a select statement. For example:

   INSERT INTO temptable (id, name) SELECT id, name FROM sometable WHERE condition;

   In this example, the data is being inserted into the "temptable" temporary table. The "id" and "name" columns are being mapped to the "id" and "name" columns of the "sometable" table using a select statement. The "condition" specifies the rows to be selected.

4. You can then query the temporary table using a SELECT statement to verify that the data has been inserted correctly. For example:

   SELECT * FROM temp_table;

   This will display all the rows in the "temp_table" temporary table.

5. Remember to drop the temporary table after you are done using it, so that it does not take up unnecessary space in the database. For example:

   DROP TABLE temp_table;

   This will delete the "temp_table" temporary table from the database.