Updating joined tables
Likewise, updating and deleting start out as simple tasks.
To that end, you’ll also find techniques for inserting many rows at a time.All brands support use of the DEFAULT keyword as a way of explicitly specifying the default value for a column.Some brands provide additional ways to solve the problem.By specifying NULL as the value for a column, you can set the column to NULL despite any default value.You want to copy rows from one table to another by using a query.For example, you want to insert rows from DEPT into tables DEPT_EAST, DEPT_WEST, and DEPT_MID.
All three tables have the same structure (same columns and data types) as DEPT and are currently empty.
In the solution provided, the expression “1 = 0” in the WHERE clause of the query causes no rows to be returned.
Thus the result of the CTAS statement is an empty table based on the columns in the SELECT clause of the query.
That may not sound like too useful a thing now, but the MERGE statement represents a very powerful way to bring a database table into sync with an external source of data (such as a flat file feed from a remote system). The value for DEPTNO should be 50, DNAME should be “PROGRAMMING”, and LOC should be “BALTIMORE”.
The INSERT statement allows you to create new rows in database tables.
The result is an empty table based on the columns in the SELECT clause of the query.