A relational symbol representing natural joins between tables in database theory or matched pairs in category theory.
Examples
Natural join operation in relational algebra (databases)
R \bowtie S
Composition of relations with matching domains
R_1 \bowtie R_2 = \{(x,y) \mid \exists z: (x,z) \in R_1 \land (z,y) \in R_2\}
Multiple relation joins in database queries
\text{Employee} \bowtie \text{Department} \bowtie \text{Location}