CST Week 4 Learning Journal

 Part 1: 5 things I have learned so far

We are now halfway through CST 363. Below is what I have learned so far: 

1. In database design, where large databases are needed, there are three phases to ensure the database's functionality. First, we need to complete an analysis of the database and identify the entities, relationships, and attributes. Then, we need to develop the logical design of the table, which shows the columns, rows, and table names and identifies items such as keys. The final step is the physical design which includes adding indexes and specifies how data is organized on storage media. 
   
2. Within the database design, the logical design is more important as it affects query results. The physical design affects query processing speed but not the result. 
3. A relational data structure is based on set theory, where a set is an unordered collection of elements, and a tuple is an ordered collection of elements. 
4. To write queries, we use SQL statements to insert, select, delete, and update data from the table. We can create tables using the CREATE keyword and identify the columns with their data type and whether they are keys. 
5. Various predicates, operators, functions, and clauses can be used in combination with SQL statements to return data from a table. Some predicates and operators include 'between' and 'like'. The two mentioned give restrictions to a column or columns when performing a search. Various functions can be used in conjunction with SQL statements. The functions range from numerical to string to date and time functions. Aggregated functions such as count(), min(), and max() can be used to help filter the desired data. Clauses such as 'distinct' and 'order by' organize the data and can even help with selecting the intended data. 

Part 2: Questions I have so far

Along with learning about databases, I also still have some questions regarding our most recent material. 

1. Once a database is set up and functioning properly, how can it be changed/updated while keeping previous information intact? 
2. What happens when the storage media is full of data? Is another one brought in to take over? 
3. Is it wise to organize a table (alphabetically by name, sorted by group, etc.) before a query is implemented, or should that only be done with queries (if needed)?