2006-06-29 07:08:32 · 2 answers · asked by showri 1 in Computers & Internet ➔ Software
Sometimes we have to select data from two or more tables to make our result complete. We have to perform a join.
Tables in a database can be related to each other with keys. A primary key is a column with a unique value for each row. The purpose is to bind data together, across tables, without repeating all of the data in every table.
2006-06-29 07:17:46 · answer #1 · answered by John 3 · 0⤊ 0⤋
Join in any SQL language means you join two tables together. for example when you run a query and want to retrieve answers from two tables you have to join the tables. In the SQL server it can be done graphically by creating a relationship but also manually by inserting it into the SQL query. Uses just tells the query which table to use to get the result. Those are simple SQL key words. I know in the world of SQL 2000 and 2005 lots is being done graphically, but there is no comparison to learning the raw SQL first.
2006-06-29 07:18:26 · answer #2 · answered by yairs2000 3 · 0⤊ 0⤋