3. (help me translate.tapi ini masih pengertiannya sih )
join =
An SQL JOIN clause combines records from two or more tables in a database. It creates a set that can be saved as a table or used as is. A JOIN is a means for combining fields from two tables by using values common to each. ANSI standard SQL specifies four types of JOINs: INNER, OUTER, LEFT, and RIGHT. In special cases, a table (base table, view, or joined table) can JOIN to itself in a self-join.
A programmer writes a JOIN predicate to identify the records for joining. If the evaluated predicate is true the combined record is then produced in the expected format, for example a record set or a temporary table.
where=
clause in SQL specifies that a SQL Data Manipulation Language (DML) statement should only affect rows that meet a specified criteria. The criteria is expressed in form of predicates. WHERE clauses are not mandatory clauses of SQL DML statements, but should be used to limit the number of rows affected by a SQL DML statement or returned by a query.WHERE is an SQL reserved word.