by Polun L
The article, “Writing SQL Statements That Use Joins to Combine Data from Multiple Tables”, is briefly related to our this week class materials which are combining data from multiple tables by using joins. Where clause is used to bring data from more than one table into a set of query. If it does not include where clause, the return would be huge and meaningless because the select statement matches every record with each customer for the return. The second join has two clause types, inner join and outer join. Inner join creates a record set when they match records from both table while outer join creates a record set from a specified table and a related look up table that matches records in the master table. Also, users can apply an outer join with either left join clause or right join clause. These two different joins represents the order in which users specify a master table or a look up table.
This article is kind of a preview of what I am going to learn in the class this week. It may help me understand easily when I go through this material in the class.
www.freetutes.com. (n.d.). Visual basic tutorial. Retrieved from http://visualbasic.freetutes.com/learn-vb6-advanced/lesson9/p20.html