INSERT Command in SQL

Loosely speaking, INSERT takes the rows of a given source table and adds them to the specified target table, retaining all the existing rows in the target.

Example shows how INSERT can be used to add a single row to IS_ENROLLED_ON.

Example: Enrolling a student on a course using INSERT

INSERT INTO IS_ENROLLED_ON VALUES ('S3', 'C2');

Recall that VALUES ('S3', 'C2') denotes the table consisting of just the row ('S3', 'C2'). If that row already exists in the target table, then the update has the effect of increasing the number of appearances of that row by one, unless some key is specified for that table (as is the case with IS_ ENROLLED_ON), in which case the update fails.