To transfer the data set of $50,000$ tuples from database schema$1$ to database schema$2$ at the database level, John can use the following SQL query:

INSERT INTO schema$2.$table$2($col$1,$ col$2,$ col$3,$ col$4,$ col$5)$

SELECT col$1,$ col$2,$ col$3,$ col$4,$ col$5$

FROM schema$1.$table$1$;

This query will insert the data from schema$1.$table$1$ into schema$2.$table$2.$ Since table$1$ has seven attributes and table$2$ has five attributes, the two extra attributes in table$1$ will be lost. The remaining five attributes will be inserted into table$2.$

Here is a diagrammatic representation of the two tables:

schema$1.$table$1$

$+------+-------+-------+-------+-------+------------+---------------------+$

$|$ col$1|$ col$2|$ col$3|$ col$4|$ col$5|$ updatedBy $|$ updatedAt $|$

$+------+-------+-------+-------+-------+------------+---------------------+$

$|...|...|...|...|...|...|...|$

$|...|...|...|...|...|...|...|$

$|...|...|...|...|...|...|...|$

$+------+-------+-------+-------+-------+------------+---------------------+$

schema$2.$table$2$

$+------+-------+-------+-------+-------+$

$|$ col$1|$ col$2|$ col$3|$ col$4|$ col$5|$

$+------+-------+-------+-------+-------+$

$|...|...|...|...|...|$

$|...|...|...|...|...|$

$|...|...|...|...|...|$

$+------+-------+-------+-------+-------+$

As for the most efficient technique, it depends on the specific requirements of the transfer. Some techniques may be more efficient for certain scenarios than others. However, one common technique is to use a bulk insert operation, which can be faster than inserting each tuple individually. Another technique is to use a temporary table to store the data before transferring it to the destination table. This can help to reduce the amount of time that the source table is locked during the transfer. Ultimately, the most efficient technique will depend on the specific requirements of the transfer and the characteristics of the database system being used. Please provide example SQL diagrams and show all design