using aliases:
SELECT a.some_fields, b.other_fields
FROM table a, table b
WHERE a.foreign_key=b.primary_key;
join combine the two table to gv a resultant set
A SQL join clause combines records from two or sometimes more than two tables in to a database. This creates a set that can be used as it is or can be saved as a table.
Outer Join in SQL is used to retrieve all records from one table and only matching records from another table. It helps to retrieve data from related tables even if there are no matching records in one of the tables.
Yes. In MySQL you can join a table to itself. You must use different alias name for each instance.
A semi-join returns rows from one table that would join with another table without performing a complete join. It doesn't have explicit syntax. Eg : semi join to evaluate an exists sub query select * from Customers C where exists ( select * from Sales S where S.Cust_Id = C.Cust_Id ) Cust_Id Cust_Name ----------- ---------- 2 John Doe 3 Jane Doe
Joins refer to the combination of related records to form a relation . There are six types of joins in database . Types of joins are cross join, natural join , right join , left join ,Inner join, Outer join.INNER JOINOUTER JOINLEFT JOINRIGHT JOINNATURAL JOINCROSS JOINIn special cases a table can join to itself (SELF JOIN)
temp table
Using a left join of: SELECT a.number FROM table a, table b WHERE a.number < b.number where right table.number is null
Some of the operations performed in DDL in sql are creation of table,alteration of table,truncate a table, drop a table
Inner Join
Cross Join is jsut another Join
SQL is a special language for making queries to databases. An outer join is a special form of joining two tables within the database, when a SELECT query is made. In the outcome of the query you will find all selected entries from the so called "left table" (the table that was target of the select query) and only those entries from the "right table" (the one that is joined with the other) that fit a specified joining condition.