Informatics Practices · Ch 1 — Querying and SQL Functions
Intersect (∩)
Intersect (∩)
The INTERSECT operation, denoted by the symbol ∩, is used to find common tuples (rows) that appear in two tables. Figure 1.4 shows this as a Venn diagram — think of it as the overlapping region when you draw two circles; only the items present in both circles are kept.
Using the same DANCE and MUSIC relations from the previous section, if you need a list of students taking part in both events, you apply the INTERSECT operation on these two tables.
The result of DANCE ∩ MUSIC — shown in Table 1.13 — is a new table containing only those rows that exist in both the Dance table and the Music table: Mahira (SNo 2, Class 6A) and Sanjay (SNo 4, Class 7A) are the only students enrolled in both events.
The INTERSECT operation is the set-theoretic intersection. It removes duplicates automatically and returns only distinct rows that are common to both input tables. …
Drawn by us to help you understand the concept clearly, and verified to make sure it's accurate. For exams, practice from your textbook's own diagram.
The figure is a Venn diagram with two overlapping circles, no surrounding rectangle. The left circle is labelled Music, the right circle is labelled Dance. The region where the two circles overlap — the lens-shaped area common to both — is shaded. The rest of each circle (the parts of Music that do not overlap with Dance, and the parts of Dance that do not overlap with Music) is left unshaded. …
| SNo | Name | Class |
|---|---|---|
| 2 | Mahira | 6A |