CIS105: Computer Applications & Information Systems Lect. 17 ​

Chapter 17: SQL Clauses: JOIN Query ​

17.1: JOIN & ON Clauses ​

• JOIN: Join tables together to connect multiple fields into 1 query.
• ON: Linking the primary and foreign key
• Linking formula: FROM table1 + JOIN table2 ON table1.primarykey = table2.foreignkey

SELECT first_name, last_name, link_to_major, major_id, major_name
	FROM member
	JOIN major
		ON member. link_to_major = major.major_id

SELECT first_name, last_name, link_to_major, major_id, major_name
	FROM member
	JOIN major
		ON member. link_to_major = major.major_id

17.2: SQL Statements: Primary vs. Foreign Keys ​

• Primary key: A field on a database table that uniquely identifies each row of the table.
• Foreign key: is used to combine the rows from one table wit the rows of another table.

17.3: SQL Statement: Date & Time Formatting ​

• The common conventional format of SQL date & time searching is as followed, in form of YEAR-MONTH-DATT12:00:00

  • sql

    '2022-04-17T12:00:00'

    '2022-04-17T12:00:00'

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