MIS 325 Lecture Notes - Lecture 8: 2 On, Cardinality, Result Set

• School: UT-Austin
• Department: Management Information Systems
• Course: MIS 325
• Professor: Ayvaci

Document Summary

Qualified column name: need when two columns in a join condition have the same name. Code by entering the table name and a period in front of the column name. Must qualify a column name anywhere it appears in the statement if the same name occurs in both tables. Ad hoc relationships: joining tables based on relationships not defined in the database. Implicit (theta): convert same join task without using join keywords. Tables to be joined are listed in the from clause. Join conditions are included in the where clause. Similar to column alias, except does not use as. Use alias in place of original table name throughout the query. Joining to a table in another schema: schema_name. table_name. Self-join: a join where a table is joined with itself. Must qualify each column name with the alias. To join n tables, you need n - 1 join statements. You can combine inner and outer joins within a single select statement.